Known issues


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Asset tracker

NCSDK-6898: Setting CONFIG_SECURE_BOOT does not work

The immutable bootloader is not able to find the required metadata in the MCUboot image. See the related NCSDK-6898 known issue in Build system for more details.

Workaround: Set CONFIG_FW_INFO in MCUboot.

External antenna performance setting

The preprogrammed Asset Tracker does not come with the best external antenna performance.

Workaround: If you are using nRF9160 DK v0.15.0 or higher and Thingy:91 v1.4.0 or higher, set CONFIG_NRF9160_GPS_ANTENNA_EXTERNAL to y. Alternatively, for nRF9160 DK v0.15.0, you can set the CONFIG_NRF9160_GPS_COEX0_STRING option to AT%XCOEX0 when building the preprogrammed Asset Tracker to achieve the best external antenna performance.

NCSDK-5574: Warnings during FOTA

The nRF9160: Asset Tracker application prints warnings and error messages during successful FOTA.

NCSDK-6689: High current consumption in Asset Tracker

The nRF9160: Asset Tracker might show up to 2.5 mA current consumption in idle mode with CONFIG_POWER_OPTIMIZATION_ENABLE set to y.

Sending data before connecting to nRF Cloud

The nRF9160: Asset Tracker application does not wait for connection to nRF Cloud before trying to send data. This causes the application to crash if the user toggles one of the switches before the kit is connected to the cloud.

IRIS-2676: Missing support for FOTA on nRF Cloud

The nRF9160: Asset Tracker application does not support the nRF Cloud FOTA_v2 protocol.

Workaround: The implementation for supporting the nRF Cloud FOTA_v2 can be found in the following commits:

  • cef289b559b92186cc54f0257b8c9adc0997f334

  • 156d4cf3a568869adca445d43a786d819ae10250

  • f520159f0415f011ae66efb816384a8f7bade83d

Asset Tracker v2

CIA-463: Wrong network mode parameter reported to cloud

The network mode string present in deviceInfo (nRF Cloud) and dev (Azure IoT Hub and AWS IoT) JSON objects that is reported to cloud might contain wrong network modes. The network mode string contains the network modes that the modem is configured to use, not what the modem actually connects to the LTE network with.

NCSDK-14235: Timestamps that are sent in cloud messages drift over time

Due to a bug in the Date-Time library, timestamps that are sent to cloud drift because they are calculated incorrectly.

CIA-604: ATv2 cannot be built for the thingy91_nrf9160_ns build target with SECURE_BOOT enabled

Due to the use of static partitions with the Thingy:91, there is insufficient room in the flash memory to enable both the primary and secondary bootloaders.

CIA-661: Asset Tracker v2 application configured for LwM2M cannot be built for the nrf9160dk_nrf9160_ns build target with modem traces or memfault enabled

The nRF9160: Asset Tracker v2 application configured for LwM2M cannot be built for the nrf9160dk_nrf9160_ns build target with CONFIG_NRF_MODEM_LIB_TRACE for modem traces or overlay-memfault.conf for memfault due to memory constraints.


Use one of the following workarounds for modem traces:

For memfault, use Secure Partition Manager instead of TF-M by setting CONFIG_SPM to y and CONFIG_BUILD_WITH_TFM to n.

Serial LTE Modem

NCSDK-13895: Build failure for target Thingy:91 with secure_bootloader overlay

Building the application for Thingy:91 fails if secure_bootloader overlay is included.

Other issues

NCSDK-15512: Modem traces retrieval incompatible with TF-M

Enabling modem traces with CONFIG_UART NRF_MODEM_LIB_TRACE_BACKEND_UART set to y will disable TF-M logging from secure processing environment (using CONFIG_TFM_LOG_LEVEL_SILENCE set to y) including output from hardware fault handlers. You can either use UART1 for TF-M output or for modem traces, but not for both.

NCSDK-15471: Compilation with SUPL client library fails when TF-M is enabled

Building an application that uses the SUPL client library fails if TF-M is used.

Workaround: Use one of the following workarounds:

CIA-351: Connectivity issues with Azure IoT Hub

If a device-bound message is sent to the device while it is in the LTE Power Saving Mode (PSM), the TCP connection will most likely be terminated by the server. Known symptoms of this are frequent reconnections to cloud, messages sent to Azure IoT Hub never arriving, and FOTA images being downloaded twice.

Workaround: Avoid using LTE Power Saving Mode (PSM) and extended DRX intervals longer than approximately 30 seconds. This will reduce the risk of the issue occurring, at the cost of increased power consumption.

NCSDK-10106: Elevated current consumption when using applications without Modem library on nRF9160

When running applications that do not enable Modem library on nRF9160 with build code B1A, current consumption will stay at 3 mA when in sleep.

Workaround: Enable Modem library.

NCSDK-8075: Invalid initialization of mbedtls_entropy_context mutex type

The calls to mbedtls_entropy_init() do not zero-initialize the member variable mutex when nrf_cc3xx is enabled.

Workaround: Zero-initialize the structure type before using it or make it a static variable to ensure that it is zero-initialized.

Receive error with large packets

nRF91 fails to receive large packets (over 4000 bytes).

The time returned by Date-Time library becomes incorrect after one week of uptime

The time returned by Date-Time library becomes incorrect after one week elapses. This is due to an issue with clock_gettime() API.

NCSDK-12912: LwM2M carrier library does not recover if initial network connection fails

When the device is switched on, if lte_lc_connect() returns an error at timeout, it will cause lwm2m_carrier_init() to fail. Thus, the device will fail to connect to carrier device management servers.

Workaround: Increase CONFIG_LTE_NETWORK_TIMEOUT to allow LTE link controller more time to successfully connect.

NCSDK-12913: LwM2M carrier library will fail to initialize if phone number is not present in SIM

The SIM phone number is needed during the LwM2M carrier library start-up. For new SIM cards, it may take some time before the phone number is received by the network. The LwM2M carrier library does not wait for this to happen. Thus, the device can fail to connect to the carrier’s device management servers.

Workaround: Use one of the following workarounds:

  • Reboot or power-cycle the device after the SIM has received a phone number from the network.

  • Apply the following commits, depending on your nRF Connect SDK version:

NCSDK-13106: When replacing a Verizon SIM card, the LwM2M carrier library does not reconnect to the device management servers

When a Verizon SIM card is replaced with a new Verizon SIM card, the library fails to fetch the correct PSK for the bootstrap server. Thus, the device fails to connect to the carrier’s device management servers.

Workaround: Use one of the following workarounds:

  • Use the CONFIG_LWM2M_CARRIER_USE_CUSTOM_PSK and CONFIG_LWM2M_CARRIER_CUSTOM_PSK configuration options to set the appropriate PSK needed for Verizon test or live servers. This PSK can be obtain from the carrier.

  • After inserting a new SIM card, reboot the device again.

NCSDK-11684: Failure loading KMU registers on nRF9160 devices

Certain builds will experience problems loading HUK to KMU due to a bug in nrf_cc3xx_platform library prior to version 0.9.12. The problem arises in certain builds depending on alignment of code. The reason for the issue is improper handling of PAN 7 on nRF9160 devices.

Workaround: Update to nrf_cc3xx_platform/nrf_cc3xx_mbedcrypto v0.9.12 or newer versions if KMU is needed.

NCSDK-11033: Dial-up usage not working

Dial-up usage with MoSh PPP does not work and causes the nRF9160 DK to crash when it is connected to a PC.

Workaround: Manually pick the fix available in Zephyr to the Zephyr issue #38516.

NCSDK-7856: Faulty indirection on nrf_cc3xx memory slab when freeing the platform mutex

The mutex_free_platform() function has a bug where a call to k_mem_slab_free() provides wrong indirection on a parameter to free the platform mutex.

Workaround: Write the call to free the mutex in the following way: k_mem_slab_free(&mutex_slab, &mutex->mutex). The change adds & before the parameter mutex->mutex.

NCSDK-7914: The nrf_cc3xx RSA implementation does not deduce missing parameters

The calls to mbedtls_rsa_complete() will not deduce all types of missing RSA parameters when using nrf_cc3xx v0.9.6 or earlier.

Workaround: Calculate the missing parameters outside of this function or update to nrf_cc3xx v0.9.7 or later.

NRF91-989: Unable to bootstrap after changing SIMs

In some cases, swapping the SIM card may trigger the bootstrap Pre-Shared Key to be deleted from the device. This can prevent future bootstraps from succeeding.

NCSDK-5666: LTE Sensor Gateway

The nRF9160: LTE Sensor Gateway sample crashes when Thingy:52 is flipped.

NCSDK-6073: nrf_send is blocking

The nrf_send() function in the Modem library might be blocking for several minutes, even if the socket is configured for non-blocking operation. The behavior depends on the cellular network connection.

Workaround: For nRF Connect SDK v1.4.0, set the non-blocking mode for a partial workaround for non-blocking operation.

GPS sockets and SUPL client library stops working

The nRF9160: GPS with SUPL client library sample stops working if SUPL client and SUPL client OS integration support is enabled, but the SUPL host name cannot be resolved.

Workaround: Insert a delay (k_sleep()) of a few seconds after the printf on line 294 in main.c.

Calling nrf_connect() immediately causes fail

nrf_connect() fails if called immediately after initialization of the device. A delay of 1000 ms is required for this to work as intended.

Problems with RTT Viewer/Logger

The SEGGER Control Block cannot be found by automatic search by the RTT Viewer/Logger.

Workaround: Set the RTT Control Block address to 0 and it will try to search from address 0 and upwards. If this does not work, look in the builddir/zephyr/ file to find the address of the _SEGGER_RTT symbol in the map file and use that as input to the viewer/logger.

Modem FW reset on debugger connection through SWD

If a debugger (for example, J-Link) is connected through SWD to the nRF9160, the modem firmware will reset. Therefore, the LTE modem cannot be operational during debug sessions.

NCSDK-9441: Fmfu SMP server sample is unstable with the newest J-Link version

Full modem serial update does not work on development kit with debugger chip version delivered with J-Link software > 6.88a

Workaround: Downgrade the debugger chip to the firmware released with J-Link 6.88a or use another way of transferring serial data to the chip.



NCSDK-16338: Setting gain for nRF21540 Front-end module does not work in the Radio test sample

Workaround: Enable the SPI 0 instance in the nRF5340 network core DTS overlay file.

NCSDK-11432: DFU: Erasing secondary slot returns error response

Trying to erase secondary slot results in an error response. Slot is still erased. This issue is only occurring when the application is compiled for multi-image.

NCSDK-9786: Wrong FLASH_PAGE_ERASE_MAX_TIME_US for the nRF53 network core

FLASH_PAGE_ERASE_MAX_TIME_US defines the execution window duration when doing the flash operation synchronously along the radio operations (CONFIG_SOC_FLASH_NRF_PARTIAL_ERASE not enabled).

The FLASH_PAGE_ERASE_MAX_TIME_US value of the nRF53 network core is lower than required. For this reason, if CONFIG_SOC_FLASH_NRF_RADIO_SYNC_MPSL is set to y and CONFIG_SOC_FLASH_NRF_PARTIAL_ERASE is set to n, a flash erase operation on the nRF5340 network core will result in an MPSL timeslot OVERSTAYED assert.

Workaround: Increase FLASH_PAGE_ERASE_MAX_TIME_US (defined in ncs/zephyr/soc/arm/nordic_nrf/nrf53/soc.h) from 44850UL to 89700UL (the same value as for the application core).

NCSDK-7234: UART output is not received from the network core

The UART output is not received from the network core if the application core is programmed and running with a non-secure image (using the nrf5340dk_nrf5340_cpuapp_ns build target).

KRKNWK-6756: 802.15.4 Service Layer (SL) library support for the nRF53

The binary variant of the 802.15.4 Service Layer (SL) library for the nRF53 does not support such features as synchronization of TIMER with RTC or timestamping of received frames. For this reason, 802.15.4 features like delayed transmission or delayed reception are not available for the nRF53.

FOTA does not work

FOTA with the SMP Server Sample does not work.

NCSDK-13925: Build warning in the RF test samples when the nRF21540 EK support is enabled

Radio test and Bluetooth: Direct Test Mode build with warnings for nRF5340 with the nRF21540 EK support.

Workaround: Change the parameter type in the nrf21540_tx_gain_set() function in ncs/nrf/samples/bluetooth/direct_test_mode/src/fem/nrf21540.c from uint8_t to uint32_t.


Missing CMakeLists.txt

The CMakeLists.txt file for developing applications that emulate nRF52820 on the nRF52833 DK is missing.

Workaround: Create a CMakeLists.txt file in the ncs/zephyr/boards/arm/nrf52833dk_nrf52820 folder with the following content:


You can download this file from the upstream Zephyr repository. After you add it, the file is automatically included by the build system.


KRKNWK-14756: Increased average latency during communication with nRF5340-based SED

The measured average latency (RTT) of the Echo Request/Response transaction sometimes shows a slight increase over the baseline when the receiver is a Sleepy End Device based on the nRF5340 SoC platform.

KRKNWK-14231: Device stops receiving after switching from SSED to MED

Trying to switch to the MED mode after working as CSL Receiver makes the device stop receiving frames.

Workaround: Before invoking otThreadSetLinkMode() to change the device mode, make sure to set the CSL Period to 0 with otLinkCslSetPeriod().

KRKNWK-9094: Possible deadlock in shell subsystem

Issuing OpenThread commands too fast might cause a deadlock in the shell subsystem.

Workaround: If possible, avoid invoking a new command before execution of the previous one has completed.

KRKNWK-6848: Reduced throughput

Performance testing for the Thread: Co-processor sample shows a decrease of throughput of around 10-20% compared with the standard OpenThread.

KRKNWK-13059: Wrong MAC frame counter is reported sometimes

The reporting of the wrong MAC frame counter causes the neighbor to drop subsequent frames from the device due to security checks. This issue only affects to Thread 1.2 builds.

Workaround: To fix the issue, update the sdk-zephyr repository by cherry-picking the commit with the hash 1ab6be252335ceec5a966b36fbc79883ebd1c4d1.

nRF Connect SDK v1.7.0 will not be certified for Thread

Due to the issues KRKNWK-11555: Devices lose connection after a long time running and KRKNWK-11264: Some boards assert during high traffic, nRF Connect SDK v1.7.0 will not undergo the certification process, and is not intended to be used in final Thread products.

KRKNWK-11555: Devices lose connection after a long time running

Connection is sometimes lost after Key Sequence update.

KRKNWK-11264: Some boards assert during high traffic

The issue appears when traffic is high during a corner case, and has been observed after running stress tests for a few hours.

Zephyr systems with OpenThread become unresponsive after some time

Systems become unresponsive after running around 49.7 days.

Workaround: Rebooting the system regularly avoids the issue. To fix the error, cherry-pick commits from the upstream Zephyr issue #39704.

KRKNWK-10633: Incorrect data when using ACK-based Probing with Link Metrics

When using the ACK-based Probing enhanced with Link Metrics, the Thread Information Element contains fixed data instead of the correct Link Metrics data for the acknowledged frame.

KRKNWK-10467: Security issues for retransmitted frames with Thread 1.2

The Thread 1.2 current implementation does not guarantee that all retransmitted frames will be secured when using the transmission security capabilities of the radio driver. For this reason, OpenThread retransmissions are disabled by default when the CONFIG_NRF_802154_ENCRYPTION Kconfig option is enabled. You can enable the retransmissions at your own risk.

KRKNWK-11037: Udp::GetEphemeralPort can cause infinite loop

Using Udp::GetEphemeralPort in OpenThread can potentially cause an infinite loop.

Workaround: Avoid using Udp::GetEphemeralPort.

KRKNWK-9461 / KRKNWK-9596Multiprotocol sample crashes with some smartphones

With some smartphones, the multiprotocol sample crashes on the nRF5340 due to timer timeout inside the 802.15.4 radio driver logic.

KRKNWK-7885: Throughput is lower when using CC310 nrf_security backend

A decrease of throughput of around 5-10% has been observed for the CC310 nrf_security backend when compared with nrf_oberon or the standard mbedtls backend. CC310 nrf_security backend is used by default for nRF52840 boards. The source of throughput decrease is coupled to the cost of RTOS mutex locking when using the CC310 nrf_security backend when the APIs are called with shorter inputs.

Workaround: Use AES-CCM ciphers from the nrf_oberon backend by setting the following options:





KRKNWK-7721: MAC counter updating issue

The RxDestAddrFiltered MAC counter is not being updated. This is because the PENDING_EVENT_RX_FAILED event is not implemented in Zephyr.

Workaround: To fix the error, cherry-pick commits from the upstream Zephyr PR #29226.

KRKNWK-7962: Logging interferes with shell output

CONFIG_LOG_MODE_MINIMAL is configured by default for most OpenThread samples. It accesses the UART independently from the shell backend, which sometimes leads to malformed output.

Workaround: Disable logging or enable a more advanced logging option.

KRKNWK-7803: Automatically generated libraries are missing otPlatLog for NCP

When building OpenThread libraries using a different sample than the Thread: Co-processor sample, the ncp_base.cpp is not compiled with the otPlatLog() function. This results in a linking failure when building the NCP with these libraries.

Workaround: Use the Thread: Co-processor sample to create OpenThread libraries.

NCSDK-5014: Building with SES not possible

It is not possible to build Thread samples using SEGGER Embedded Studio (SES). SES does not support .cpp files in nRF Connect SDK projects.

KRKNWK-6358: CoAP client sample provisioning issues

It is not possible to provision the Thread: CoAP Client sample to servers that it cannot directly communicate with. This is because Link Local Address is used for communication.

KRKNWK-6408: diag command not supported

The diag command is not yet supported by Thread in the nRF Connect SDK.


KRKNWK-14024 Fatal error when the network coordinator factory resets in the Identify mode

A fatal error occurs when the Zigbee network coordinator triggers factory reset in the Identify mode.

Workaround: Modify your application, so that the factory reset is requested only after the Identify mode ends.

KRKNWK-12937: Activation of Sleepy End Device must be done at the very first commissioning procedure for Zigbee light switch sample

After programming the Zigbee light switch sample and its first commissioning, Zigbee End Device joins the Zigbee network as a normal End Device. Pressing Button 3 does not switch the device to the Sleepy End Device configuration.

Workaround: Keep Button 3 pressed during the first commissioning procedure.

KRKNWK-12615: Get Group Membership Command returns all groups the node is assigned to

Get Group Membership Command returns all groups the node is assigned to regardless of the destination endpoint.

KRKNWK-12115: Simultaneous commissioning of many devices can cause the Coordinator device to assert

The Zigbee Coordinator device can assert when multiple devices are being commissioned simultaneously. In some cases, the device can end up in the low memory state as the result.

Workaround: To lower the likelihood of the Coordinator device asserting, increase its scheduler queue and buffer pool by completing the following steps:

  1. Create your own custom memory configuration file by creating an empty header file for your application, similar to include/zb_mem_config_custom.h header file in the Zigbee light switch sample.

  2. Copy the contents of zb_mem_config_max.h memory configuration file to the memory configuration header file you have just created. The Zigbee Network Coordinator sample uses the contents of the memory configuration file by default.

  3. In your custom memory configuration file, locate the following code:

    /* Now if you REALLY know what you do, you can study zb_mem_config_common.h and redefine some configuration parameters, like:
  4. Replace the code you have just located with the following code:

    /* Increase Scheduler queue size. */
    /* Increase buffer pool size. */
  5. To increase the scheduler queue size, replace XYZ next to ZB_CONFIG_SCHEDULER_Q_SIZE with the value of your choice, ranging from 48U to 256U.

  6. To increase the buffer pool size, replace XYZ next to ZB_CONFIG_IOBUF_POOL_SIZE with the value of your choice, ranging from 48U to 127U.

KRKNWK-11826: Zigbee Router does not accept new child devices if the maximum number of children is reached

Once the maximum number of children devices on a Zigbee Router is reached and one of them leaves the network, the Zigbee Router does not update the flags inside beacon frames to indicate that it cannot accept new devices.

Workaround: If the maximum number of child devices has been reached, call bdb_start_top_level_commissioning(ZB_BDB_NETWORK_STEERING) on the parent router from the ZB_ZDO_SIGNAL_LEAVE_INDICATION signal handler.

KRKNWK-11704: NCP communication gets stuck

The communication between the SoC and the NCP Host sometimes stops on the SoC side. The device neither sends nor accepts incoming packets. Currently, there is no workaround for this issue.

KRKNWK-12522: Incorrect Read Attributes Response on reading multiple attributes when the first attribute is unsupported

When reading multiple attributes at once and the first one is not supported, the Read Attributes Response contains two records for the first supported attribute. The first one record has the Status field filled with Unsupported Attribute whereas the second record contains actual data.

KRKNWK-12017: Zigbee End Device does not recover from broken rejoin procedure

If the Device Announcement packet is not acknowledged by the End Device’s parent, joiner logic is stopped and the device does not recover.

Workaround: Complete the following steps to detect when the rejoin procedure breaks and reset the device:

  1. Introduce helper variable joining_signal_received.

  2. Extend zigbee_default_signal_handler() by completing the following steps:

    1. Set joining_signal_received to true in the following signals: ZB_BDB_SIGNAL_DEVICE_FIRST_START, ZB_BDB_SIGNAL_DEVICE_REBOOT, ZB_BDB_SIGNAL_STEERING.

    2. If leave_type is set to ZB_NWK_LEAVE_TYPE_REJOIN, set joining_signal_received to false in the ZB_ZDO_SIGNAL_LEAVE signal.

    3. Handle the ZB_NLME_STATUS_INDICATION signal to detect when End Device failed to transmit packet to its parent, reported by signal’s status ZB_NWK_COMMAND_STATUS_PARENT_LINK_FAILURE.

See the following snippet for an example:

/* Add helper variable that will be used for detecting broken rejoin procedure. */
/* Flag indicating if joining signal has been received since restart or leave with rejoin. */
bool joining_signal_received = false;
/* Extend the zigbee_default_signal_handler() function. */
    joining_signal_received = true;
    joining_signal_received = true;
    joining_signal_received = true;
    if (status == RET_OK) {
        zb_zdo_signal_leave_params_t *leave_params = ZB_ZDO_SIGNAL_GET_PARAMS(sig_hndler, zb_zdo_signal_leave_params_t);
        LOG_INF("Network left (leave type: %d)", leave_params->leave_type);

        /* Set joining_signal_received to false so broken rejoin procedure can be detected correctly. */
        if (leave_params->leave_type == ZB_NWK_LEAVE_TYPE_REJOIN) {
            joining_signal_received = false;
    zb_zdo_signal_nlme_status_indication_params_t *nlme_status_ind =
        ZB_ZDO_SIGNAL_GET_PARAMS(sig_hndler, zb_zdo_signal_nlme_status_indication_params_t);
    if (nlme_status_ind->nlme_status.status == ZB_NWK_COMMAND_STATUS_PARENT_LINK_FAILURE) {

        /* Check for broken rejoin procedure and restart the device to recover. */
        if (stack_initialised && !joining_signal_received) {
KRKNWK-11465: OTA Client issues in the Image Block Request

OTA Client cannot send Image Block Request with MinimumBlockPeriod attribute value set to 0.

Workaround: Complete the following steps to mitigate this issue:

  1. Restore the default MinimumBlockPeriod attribute value by adding the following snippet in zigbee_fota.c file to the zigbee_fota_abort() function and to the zigbee_fota_zcl_cb function in the case where the ZB_ZCL_OTA_UPGRADE_STATUS_FINISH status is handled:

    /* Variable that store new value for MinimumBlockPeriod attribute. */
    zb_uint16_t minimum_block_period_new_value = NEW_VALUE;
    /* Set attribute value. */
    zb_uint8_t status = zb_zcl_set_attr_val(
    /* Check if new value was set correctly. */
    if (status != ZB_ZCL_STATUS_SUCCESS) {
            LOG_ERR("Failed to update Minimum Block Period attribute");
  2. In zboss/src/zcl/zcl_ota_upgrade_commands.c file in the nrfxlib directory, change the penultimate argument of the ZB_ZCL_OTA_UPGRADE_SEND_IMAGE_BLOCK_REQ macro to delay in zb_zcl_ota_upgrade_send_block_requset() and resend_buffer() functions.

KRKNWK-11602: Zigbee device becomes not operable after receiving malformed packet

When any Zigbee device receives a malformed packet that does not match the Zigbee packet structure, the ZBOSS stack asserts. In the nRF Connect SDK versions before the v1.9.0 release, the device is not automatically restarted.

Workaround: Depends on your version of the nRF Connect SDK:

  • Before the nRF Connect SDK v1.9.0: Power-cycle the Zigbee device.

  • After and including the nRF Connect SDK v1.9.0: Wait for the device to restart automatically.

Given these two options, we recommend to upgrade your nRF Connect SDK version to the latest available one.

KRKNWK-7723: OTA upgrade process restarting after client reset

After the reset of OTA Upgrade Client, the client will start the OTA upgrade process from the beginning instead of continuing the previous process.

KRKNWK-8211: Leave signal generated twice

The ZB_ZDO_SIGNAL_LEAVE signal is generated twice during Zigbee Coordinator factory reset.

KRKNWK-9714: Device association fails if the Request Key packet is retransmitted

If the Request Key packet for the TCLK is retransmitted and the coordinator sends two new keys that are different, a joiner logic error happens that leads to unsuccessful key verification.

KRKNWK-9743 Timer cannot be stopped in Zigbee routers and coordinators

The call to the zb_timer_enable_stop() API has no effect on the timer logic in Zigbee routers and coordinators.

KRKNWK-10490: Deadlock in the NCP frame fragmentation logic

If the last piece of a fragmented NCP command is not delivered, the receiving side becomes unresponsive to further commands.

KRKNWK-8478: NCP host application crash on exceeding TX_BUFFERS_POOL_SIZE

If the NCP host application exceeds the TX_BUFFERS_POOL_SIZE pending requests, the application will crash on an assertion.

Workaround: Increase the value of TX_BUFFERS_POOL_SIZE or define shorter polling interval (NCP_TRANSPORT_REFRESH_TIME).

KRKNWK-8200: Sleepy End Device halts during the commissioning

If the turbo poll is disabled in the ZB_BDB_SIGNAL_DEVICE_FIRST_START signal, SED halts during the commissioning.

Workaround: Use the development libraries link or use ZB_BDB_SIGNAL_STEERING signal with successful status to disable turbo poll. See the following snippet for an example:

/* Workaround for KRKNWK-8200 (turbo poll) */
        if (status == RET_OK) {
KRKNWK-8200: Successful signal on commissioning fail

A successful steering signal is generated if the commissioning fails during TCLK exchange.

Workaround: Use the development libraries link or check for Extended PAN ID in the steering signal handler. If it is equal to zero, handle the signal as if it had unsuccessful status. See the following snippet for an example:

/* Workaround for KRKNWK-8200 (signal status) */
        if (status == RET_OK) {
                zb_ext_pan_id_t extended_pan_id;
                if (!(ZB_IEEE_ADDR_IS_VALID(extended_pan_id))) {
                       zb_buf_set_status(bufid, -1);
                       status = -1;
KRKNWK-9461 / KRKNWK-9596: Multiprotocol sample crashes with some smartphones

With some smartphones, the multiprotocol sample crashes on the nRF5340 due to timer timeout inside the 802.15.4 radio driver logic.

KRKNWK-6348: ZCL Occupancy Sensing cluster is not complete

The ZBOSS stack provides only definitions of constants and an abstract cluster definition (sensing cluster without sensors).

Workaround: To use the sensing cluster with physical sensor, copy the implementation and extend it with the selected sensor logic and properties. For more information, see the declaring custom cluster guide.

KRKNWK-6336: OTA transfer may be aborted after the MAC-level packet retransmission

If the device receives the APS ACK for a packet that was not successfully acknowledged on the MAC level, the OTA client cluster implementation stops the image transfer.

Workaround: Add a watchdog timer that will restart the OTA image transfer.

KRKNWK-7831: Factory reset broken on coordinator with Zigbee shell

A coordinator with the Zigbee shell component enabled could assert after executing the bdb factory_reset command.

Workaround: Call the bdb_reset_via_local_action function twice to remove all the network information.

KRKNWK-6318: Device assert after multiple Leave requests

If a device that rejoins the network receives Leave requests several times in a row, the device could assert.

KRKNWK-6071: ZBOSS alarms inaccurate

On average, ZBOSS alarms last longer by 6.4 percent than Zephyr alarms.

Workaround: Use Zephyr alarms.

KRKNWK-5535: Device assert if flooded with multiple Network Address requests

The device could assert if it receives Network Address requests every 0.2 second or more frequently.

KRKNWK-9119: Zigbee shell does not work with ZBOSS development libraries

Because of changes to the ZBOSS API, the Zigbee shell library cannot be enabled when Zigbee samples are built with the ZBOSS Zigbee stack development libraries.

Workaround: Use only the production version of ZBOSS Zigbee stack when using Zigbee shell.

KRKNWK-9145: Corrupted payload in commands of the Scenes cluster

When receiving Scenes cluster commands, the payload is corrupted when using the ZBOSS Zigbee stack production libraries.

Workaround: Use the development version of ZBOSS Zigbee stack.

KRKNWK-7836: Coordinator asserting when flooded with ZDO commands

Executing a high number of ZDO commands can cause assert on the coordinator with the Zigbee shell component enabled.

KRKNWK-6073: Potential delay during FOTA

There might be a noticeable delay (~220 ms) between calling the ZBOSS API and on-the-air activity.


KRKNWK-15749: Invalid ZAP Tool revision used

The ZAP Tool revision used for the nRF Connect SDK v2.1.1 and v2.1.2 releases is not compatible with the zap files that define the Data Model in nRF Connect SDK Matter samples. This resuls in the ZAP Tool not being able to parse zap files from Matter samples.

Workaround: Check out the proper ZAP Tool revision with the following commands, where <NCS_root_directory> is the path to your nRF Connect SDK installation:

cd <NCS_root_directory>/modules/lib/matter/
git -C third_party/zap/repo/ checkout -f 2ae226
git add third_party/zap/repo/
KRKNWK-14473: Unreliable communication with the window covering sample

The window covering sample may rarely become unresponsive for a couple of seconds after commissioning to the Matter network.

Workaround: Switch from SSED to SED role.

KRKNWK-15088: Android CHIP Tool shuts down on changing the sensor type

When you change the current sensor type after activating the monitoring of another sensor type, the application shuts down.

Workaround: Restart the application and select the desired sensor type again.

KRKNWK-14748: Matter command times out when a Matter device becomes a Thread router

When a Full Thread Device becomes a router, it will ignore incoming packets for a short period of time, typically between 1-2 seconds. This may disrupt the communication over Matter and lead to transaction timeouts.

In more recent versions of Matter, this problem has been eliminated by enhancing Matter’s Message Reliability Protocol. This fix will be included in the future versions of the nRF Connect SDK.

KRKNWK-14206: CHIP Tool for Android may crash when using Cluster Interactive Tool screen

Cluster Interaction Tool screen crashes when trying to send a command that takes an optional argument.

KRKNWK-14180: The QSPI sleep mode is not handled efficiently in Matter samples on the nRF53 SoC

QSPI is active during every Bluetooth LE connection in the Matter samples that are programmed on the nRF53 SoC. This results in higher power consumption, for example during commissioning into the Matter network.

KRKNWK-11225: CHIP Tool for Android cannot communicate with a Matter device after the device reboots

CHIP Tool for Android does not implement any mechanism to recover a secure session to a Matter device after the device has rebooted and lost the session. As a result, the device can no longer decrypt and process messages sent by CHIP Tool for Android as the controller keeps using stale cryptographic keys.

Workaround: Do not reboot the device after commissioning it with CHIP Tool for Android.

KRKNWK-10589: CHIP Tool for Android crashes when commissioning a Matter device

In random circumstances, CHIP Tool for Android crashes when trying to connect to a Matter device over Bluetooth® LE.

Workaround: Restart the application and try to commission the Matter device again. If the problem persists, clear the application data and try again.

KRKNWK-12950: CHIP Tool for Android opens the commissioning window using an incorrect PIN code

CHIP Tool for Android uses a random code instead of a user-provided PIN code to open the commissioning window on a Matter device.

KRKNWK-10387: Matter service is needlessly advertised over Bluetooth® LE during DFU

The Matter samples can be configured to include the support for Device Firmware Upgrade (DFU) over Bluetooth LE. When the DFU procedure is started, the Matter Bluetooth LE service is needlessly advertised, revealing the device identifiers such as Vendor and Product IDs. The service is meant to be advertised only during the device commissioning.

KRKNWK-9214: Pigweed submodule may not be accessible from some regions

The west update command may generate log notifications about the failure to access the pigweed submodule. As a result, the Matter samples will not build.

Workaround: Execute the following commands in the root folder:

git -C modules/lib/matter submodule set-url third_party/pigweed/repo
git -C modules/lib/matter submodule sync third_party/pigweed/repo
west update


KRKNWK-13010: Dropping from Thread to Bluetooth LE takes too long

Workaround: Specification for TCT030 is going to be updated.

KRKNWK-14130: Bluetooth LE TX configuration is set to 0 dBm by default

The minimum Bluetooth LE TX configuration required is at least 4 dBm. For HomeKit multiprotocol samples, this should be 8 dBm. This results in a weak signal on the SoC itself.

Workaround: You need to configure the appropriate dBm values for Bluetooth LE and Thread manually in the source code.

KRKNWK-14081: HomeKit SDK light bulb example does not work with MTD

If the MTD is set to y in the light bulb sample, user is not able to communicate with the device after it has been added to the Home app using an iPhone and a HomePod Mini.

KRKNWK-13947: Net core downgrade prevention does not work on nRF5340

HAP certification requirements are not met because of this issue.

KRKNWK-13607: Stateless switch application crashes upon factory reset

When running Thread test suit on the stateless switch application, the CI crashes upon factory reset.

KRKNWK-13249: Unexpected assertion in HAP Bluetooth Peripheral Manager

When Bluetooth LE layer emits callback with a connect or disconnect event, one of its parameters is an underlying Bluetooth LE connection object. On rare occasions, this connection object is no longer valid by the time it is processed in HomeKit, and this results in assertion. There is no proven workaround yet.

KRKNWK-11729: Stateless switch event characteristic value not handled according to specification in Bluetooth LE mode

The stateless programmable switch application does not handle the value of the stateless switch event characteristic in the Bluetooth LE mode according to the specification. According to the specification, the accessory is expected to return null once the characteristic has been read or after 10 seconds have passed. In its current implementation in the nRF Connect SDK, the characteristic value does not change to null immediately after it is read, and changes to null after 5 seconds instead.

Workaround: The HomeKit specification in point 11.47 is going to be updated.

KRKNWK-13063: RTT logs do not work with the Light Bulb multiprotocol sample with DFU on nRF52840

The Light Bulb multiprotocol sample with Nordic DFU activated in debug version for nRF52840 platform does not display RTT logs properly.

Workaround: Disable RTT logs for the bootloader.

KRKNWK-13064: Nordic DFU is not compliant with HAP certification requirements

Some of the HAP certification requirements are not met by the Nordic DFU solution.

Workaround: Cherry-pick changes from PR #332 in sdk-homekit repo.

KRKNWK-12474: Multiprotocol samples on nRF52840 might not switch to Thread

Samples might not switch to Thread mode as expected and remain in Bluetooth mode instead. The issue is related to older iOS versions.

Workaround: Update your iPhone to iOS 15.4.

KRKNWK-13095: Change in KVS key naming scheme causes an error for updated devices

A previous implementation allowed for empty key in domain. This has been restricted during refactoring.

Workaround: Cherry-pick changes from PR #329 in sdk-homekit repo.

KRKNWK-13022: Activating DFU causes increased power consumption

Currently shell is used to initiate DFU mode, which leads to increased power consumption.

KRKNWK-10611: DFU fails with external flash memory

DFU will fail when using external flash memory for update image storage. For this reason, DFU with external flash memory cannot be performed on HomeKit accessories.

KRKNWK-9422: On-mesh commissioning does not work

Thread’s on-mesh commissioning does not work for the HomeKit accessories.

Invalid NFC payload

Invalid NFC payload occurs if the HomeKit accessory is paired.

Build error when building with DEBUG_SETUP_CODE configuration

The following build error is observed with DEBUG_SETUP_CODE - invalid file path in CMakeFile.

HomeKit accessory fails to start

Occasionally, the accessory fails to start after a factory reset attempt.

KRKNWK-11666: CLI command hap services returns incorrect results

Observed issues with the command include float values not printed, values not updated, and read callbacks shown as “<No read callback>” even though present.

KRKNWK-11365: HAP tool’s provision command freezes

This issue happens on macOS when an EUI argument is not passed in attempt to read EUI from a connected board.

nRF Desktop

NCSDK-8304: HID configurator issues for peripherals connected over Bluetooth® LE to Linux host

Using HID configurator for nRF Desktop for peripherals connected to host directly over Bluetooth LE might result in receiving improper HID feature report ID. In such case, the device will provide HID input reports, but it cannot be configured with the HID configurator.

Workaround: Use BlueZ in version 5.56 or higher.

NCSDK-13858: Possible crash at the start of Bluetooth LE advertising when using SW Split Link Layer

The nRF Desktop peripheral can crash at the start of the advertising when using SW Split Link Layer (CONFIG_BT_LL_SW_SPLIT). The crash is caused by an issue of the Bluetooth Controller. The size of the resolving list filter is invalid, which causes accessing memory areas that are located out of array.

Workaround: Manually cherry-pick and apply commit with fix to sdk-zephyr (commit hash: 15ebdfafe2b2932533aa8d71afd49d4b03d27ce4).

NCSDK-12337: Possible assertion failure at boot of an USB-connected host

During the booting procedure of a host device connected through USB, the HID report subscriptions might be disabled and enabled a few times without disconnecting the USB. This can result in improper subscription handling and assertion failure in the HID state module.

Workaround: Manually cherry-pick and apply commit with fix from main (commit hash: 3dbd4b47752671b61d13a4e5813163e9f8aef840).

NCSDK-11626: HID keyboard LEDs are not turned off when host disconnects

The HID keyboard LEDs, indicating among others state of Caps Lock and Num Lock, may not be updated after host disconnection. The problem replicates only if there is no other connected host.

Workaround: Do not use HID keyboard LEDs.

NCSDK-11378: Empty HID boot report forwarding issue

An empty HID boot report is not forwarded to the host computer by the nRF Desktop dongle upon peripheral disconnection. The host computer may not receive information that key that was previously reported as pressed was released.

Workaround: Do not enable HID boot protocol on the nRF Desktop dongle.

NCSDK-10907: Potential race condition related to HID input reports

After the protocol mode changes, the USB state module and the HID Service module modules might forward HID input reports related to the previously used protocol.

DESK-978: Directed advertising issues with SoftDevice Link Layer

Directed advertising (CONFIG_DESKTOP_BLE_DIRECT_ADV) should not be used by the nRF Desktop application when the SoftDevice Controller is in use, because that leads to reconnection problems. For more detailed information, see the Known issues and limitations section of the SoftDevice Controller’s Changelog.


The Kconfig option name changed from CONFIG_DESKTOP_BLE_DIRECT_ADV to CONFIG_CAF_BLE_ADV_DIRECT_ADV beginning with the nRF Connect SDK v1.5.99.

Workaround: Directed advertising is disabled by default for nRF Desktop.

NCSDK-12020: Current consumption for Gaming Mouse increased by 1400mA

When not in the sleep mode, the Gaming Mouse reference design has current consumption higher by 1400mA.

Workaround: Change pwm_pin_set_cycles to pwm_pin_set_usec in function led_pwm_set_brightness() in Zephyr’s driver led_pwm.c file.

NCSDK-14117: Build fails for nRF52840DK in the prj_b0_wwcb configuration

The build failure is caused by outdated Kconfig options in the nRF52840 DK’s prj_b0_wwcb configuration. The nRF52840 DK’s prj_b0_wwcb configuration does not explicitly define static partition map either.

Workaround: Manually cherry-pick and apply commit with fix from main (commit hash: cf4c465aceeb00d83a4f50edf67ce8c26427ac52).

nRF5340 Audio

OCT-2154: USB audio interface does not work correctly on macOS

The audio stream is intermittent on the headset side after connecting the gateway to a Mac computer and starting audio stream. This issue occurs sporadically after building the nRF5340 Audio application with the default USB port as the audio source.

nRF Machine Learning

NCSDK-13923: Device may crash during Bluetooth bonding

The device programmed with the nRF Machine Learning application may crash during Bluetooth bonding because of insufficient Bluetooth RX thread stack size.

Workaround: Manually cherry-pick and apply the commit with the fix from the main branch (commit hash: 4870fcd8316bd3a4b53ca0054f0ce35e1a8c567d).


NCSDK-10196: DFU fails for some configurations with the quick session resume feature enabled

Enabling CONFIG_PELION_QUICK_SESSION_RESUME together with the OpenThread network backend leads to the quick session resume failure during the DFU packet exchange. This is valid for the nRF52840 DK and the nRF5340 DK.

Workaround: Use the quick session resume feature only for configurations with the cellular network backend.

Common Application Framework (CAF)

NCSDK-13247: Sensor manager dereferences NULL pointer on wake up for sensors without trigger

CAF: Sensor manager module dereferences NULL pointer while handling a wake_up_event if a configured sensor does not use trigger. This leads to undefined behavior.

Workaround: Manually cherry-pick and apply commit with fix from main (commit hash: 3db6da76206d379c223afe2de646218e60e4f339).

NCSDK-13058: Directed advertising does not work

The directed advertising feature enabled with the CONFIG_CAF_BLE_ADV_DIRECT_ADV option does not work as intended. Using directed advertising towards peers that enable privacy may result in connection establishing problems.

Workaround: Manually cherry-pick and apply commit with fix from main (commit hash: c61c677872943bcf7905ddeec8b24b07ae50752e).

NCSDK-15675: Possible advertising start failure and module state error in CAF: Bluetooth LE advertising module

If a new peer is selected twice in a quick succession, the second peer selection may cause an advertising start failure and a module state error reported by the CAF: Bluetooth LE advertising module. See the commit with fix mentioned in the workaround for details.

Workaround: Manually cherry-pick and apply commit with fix from main (commit hash: 934a25ac23125758e350b64bca23885486682109).

NCSDK-15707: Visual glitches when updating an RGB LED’s color in CAF: LEDs module

Due to changes in the default DTS of the boards, the default PWM period has been increased. The first LED channel is updated one PWM period before other channels. This causes visual glitches for LEDs with more than one color channel when the LED color is being updated. A shorter LED PWM period mitigates the observed issue. See CAF: LEDs module for more information.

Workaround: Make sure your application includes the devicetree overlay file in which PWM period is decreased. For example, include the following commit to solve the issue for the nRF Machine Learning application for Nordic Thingy:53: fa2b57cddbaacf393c77def5d0302e1a45138d21.


Bluetooth® LE

DRGN-17695: The BT RX thread stack might overflow if the CONFIG_BT_SMP is enabled

When performing SMP pairing MPU FAULTs may be triggered because the stack is not large enough.

Workaround: Increase the stack size manually in the project configuration file (prj.conf) using CONFIG_BT_RX_STACK_SIZE.

NCSDK-15527: Advertising in the Bluetooth: Peripheral Heart Rate Monitor with Coded PHY sample and scanning in the Bluetooth: Central Heart Rate Monitor with Coded PHY sample cannot be started when using the SW Split Link Layer

The CONFIG_BT_CTLR_ADV_EXT option required by these samples is disabled by default in the SW Split Link Layer.

Workaround: Enable the CONFIG_BT_CTLR_ADV_EXT option in the project configuration file (prj.conf).

NCSDK-15229: Incorrect peer’s throughput calculation in the Bluetooth: Throughput sample

The peer’s measured throughput is understated because it includes a delay, during which there is no data transfer.

Workaround: Manually cherry-pick and apply commit with fix from main (commit hash: 05871f9b9c2aebf0a3c188a61b3788baea783180).

NCSDK-16060: Bluetooth: Peripheral LBS sample build fails when the CONFIG_BT_LBS_SECURITY_ENABLED option is disabled

Build failure is caused by the undefined conn_auth_info_callbacks structure.

Workaround: Manually cherry-pick and apply commit with fix from main (commit hash: 32c827b20f3c5ab85a359e572d366da310fe2767).

NCSDK-15724: Bluetooth’s Peripheral UART sample fails to start on Thingy:53

Enabling USB by the Peripheral UART’s main function ends with error because the USB was already enabled by the Thingy:53-specific code.

Workaround: Manually cherry-pick and apply commit with fix from main (commit hash: b834ff8860f3a30fe19c99dbf4c0c99b0b017245).

NCSDK-13459: Uninitialized size in hids_boot_kb_outp_report_read

When reading from the boot keyboard output report characteristic, the GATT Human Interface Device (HID) Service calls the registered callback with uninitialized report size.

Workaround: Manually cherry-pick and apply commit with fix from main (commit hash: f18250dad6cbd9778de7af4b8a774b58e55fe720).

NCSDK-12886: Peripheral UART sample building issue with nRF52811

The Bluetooth: Peripheral UART sample built for nRF52811 asserts on the nRF52840 DK in rev. 2.1.0 (build target: nrf52840dk_nrf52811).

NCSDK-9820: Notification mismatch in Bluetooth: Peripheral LBS

When testing the Bluetooth: Peripheral LBS sample, if you press and release Button 1 while holding one of the other buttons, the notification for button release is the same as for the button press.

NCSDK-9106: Bluetooth® ECC thread stack size too small

The Bluetooth ECC thread used during the pairing procedure with LE Secure Connections might overflow when an interrupt is triggered when the stack usage is at its maximum.

Workaround: Increase the ECC stack size by setting CONFIG_BT_HCI_ECC_STACK_SIZE to 1140.

DRGN-15435: GATT notifications and Writes Without Response might be sent out of order

GATT notifications and Writes Without Response might be sent out of order when not using a complete callback.

Workaround: Always set a callback for notifications and Writes Without Response.

DRGN-15448: Incomplete bond overwrite during pairing procedure when peer is not using the IRK stored in the bond

When pairing with a peer that has deleted its bond information and is using a new IRK to establish the connection, the existing bond is not overwritten during the pairing procedure. This can lead to MIC errors during reconnection if the old LTK is used instead.

NCSDK-8321: NUS shell transport sample does not display the initial shell prompt

NUS shell transport sample does not display the initial shell prompt uart:~$ on the remote terminal. Also, few logs with sending errors are displayed on the terminal connected directly to the DK. This issue is caused by the shell being enabled before turning on the notifications for the NUS service by the remote peer.

Workaround: Enable the shell after turning on the NUS notifications or block it until turning on the notifications.

NCSDK-8224: Callbacks for “security changed” and “pairing failed” are not always called

The pairing failed and security changed callbacks are not called when the connection is disconnected during the pairing procedure or the required security is not met.

Workaround: Application should use the disconnected callback to handle pairing failed.

NCSDK-8223: GATT requests might deadlock RX thread

GATT requests might deadlock the RX thread when all TX buffers are taken by GATT requests and the RX thread tries to allocate a TX buffer for a response. This causes a deadlock because only the RX thread releases the TX buffers for the GATT requests. The deadlock is resolved by a 30 second timeout, but the ATT bearer cannot transmit without reconnecting.


NCSDK-6845: Pairing failure with simultaneous pairing on multiple connections

When using LE Secure Connections pairing, the pairing fails with simultaneous pairing on multiple connections. The failure reason is unspecified.

Workaround: Retry the pairing on the connections that failed one by one after the pairing procedure has finished.

NCSDK-6844: Security procedure failure can terminate GATT client request

A security procedure terminates the GATT client request that is currently in progress, unless the request was the reason to initiate the security procedure. If a new GATT client request is queued at this time, this might potentially cause a GATT transaction violation and fail as well.

Workaround: Do not initiate a security procedure in parallel with GATT client requests.

NCSDK-5711: High-throughput transmission can deadlock the receive thread

High-throughput transmission can deadlock the receive thread if the connection is suddenly disconnected.

Only secure applications can use Bluetooth® LE

Bluetooth LE cannot be used in a non-secure application, for example, an application built for the nrf5340_dk_nrf5340_cpuappns build target.

Workaround: Use the nrf5340_dk_nrf5340_cpuapp build target instead.

Peripheral HIDS keyboard sample cannot be used with nRF Bluetooth® LE Controller

The Bluetooth: Peripheral HIDS keyboard sample cannot be used with the SoftDevice Controller because the NFC subsystem does not work with the controller library. The library uses the MPSL Clock driver, which does not provide an API for asynchronous clock operation. NFC requires this API to work correctly.

Peripheral HIDS mouse sample advertising issues

When the Bluetooth: Peripheral HIDS mouse sample is used with the Zephyr Bluetooth® LE Controller, directed advertising does not time out and the regular advertising cannot be started.

Central HIDS sample issues with directed advertising

The Bluetooth: Central HIDS sample cannot connect to a peripheral that uses directed advertising.

Unstable samples

Bluetooth® Low Energy peripheral samples are unstable in some conditions (when pairing and bonding are performed and then disconnections/re-connections happen).

CONFIG_BT_SMP alignment requirement

When running the Bluetooth: Central SMP Client sample, the CONFIG_BT_SMP configuration must be aligned between this sample and the Zephyr counterpart (SMP Server Sample). However, security is not enabled by default in the Zephyr sample.

Reconnection issues on some operating systems

On some operating systems, the nRF Desktop application is unable to reconnect to a host.

Bluetooth: Central UART cannot handle long strings

A too long 212-byte string cannot be handled when entered to the console to send to Bluetooth: Peripheral UART.

Bluetooth: Central HIDS loses UART connectivity

After programming a HEX file to the nrf52_pca10040 board, UART connectivity is lost when using the Bluetooth® LE Controller. The board must be reset to get UART output.

Samples crashing on nRF51 when using GPIO

On nRF51 devices, Bluetooth® LE samples that use GPIO might crash when buttons are pressed frequently. In such case, the GPIO ISR introduces latency that violates real-time requirements of the Radio ISR. nRF51 is more sensitive to this issue than nRF52 (faster core).

GATT Discovery Manager missing support

The GATT Discovery Manager is not supported on nRF51 devices.

Samples do not work with SD Controller v0.1.0

Bluetooth® LE samples cannot be built with the SoftDevice Controller v0.1.0.

LED Button Service reporting issue

Bluetooth: Peripheral LBS does not report the Button 1 state correctly.

MITM protection missing for central samples

The central samples (Bluetooth: Central UART, Bluetooth: Central HIDS) do not support any pairing methods with MITM protection.

Peripheral UART string size issue

Bluetooth: Peripheral UART cannot handle the corner case that a user attempts to send a string of more than 211 bytes.

Reconnection issues after bonding

The peripheral samples (Bluetooth: Peripheral UART, Bluetooth: Peripheral LBS, Bluetooth: Peripheral HIDS mouse) have reconnection issues after performing bonding (LE Secure Connection pairing enable) with nRF Connect for Desktop. These issues result in disconnection.

Bluetooth mesh

NCSDK-16800: RPL is not cleared on IV index recovery

After recovering the IV index, a node doesn’t clear the replay protection list, which leads to incorrect triggering of the replay attack protection mechanism.

Workaround: Call bt_mesh_rpl_reset twice after the IV index recovery is done.

NCSDK-16798: Friend Subsciption List may have duplicate entries

If a Low Power node loses a Friend Subscription List Add Confirm message, it repeats the request. The Friend does not check both the transaction number and the presence of the addresses in the subscription list. This causes a situation where the Friend fills the subscription list with duplicate addresses.

NCSDK-16782: The extended advertiser may not work with Bluetooth mesh

Using the extended advertiser instead of the legacy advertiser can lead to getting composition data while provisioning to fail. This problem may manifest in the sample Bluetooth: Mesh and peripheral coexistence, as it is using the extended advertiser.

NCSDK-16579: Advertising Node Identity and Network ID may not work with the extended advertiser

Advertising Node Identity and Network ID do not work with the extended advertising API when the CONFIG_BT_MESH_ADV_EXT_GATT_SEPARATE option is enabled.

Workaround: Don’t enable the CONFIG_BT_MESH_ADV_EXT_GATT_SEPARATE option.

NCSDK-14399: Legacy advertiser can occasionally do more message retransmissions than requested

When using the legacy advertiser, the stack sleeps for at least 50 ms after starting advertising a message, which may result in more messages to be advertised than requested.

NCSDK-16061: IV update procedure fails on the device

Bluetooth® mesh device does not undergo IV update and fails to participate in the procedure initiated by any other node unless it is rebooted after the provisioning.

Workaround: Reboot the device after provisioning.

NCSDK-10200: The device stops sending Secure Network Beacons after re-provisioning

Bluetooth® mesh stops sending Secure Network Beacons if the device is re-provisioned after reset through Config Node Reset message or bt_mesh_reset() call.

Workaround: Reboot the device after re-provisioning.

NCSDK-5580: nRF5340 only supports SoftDevice Controller

On nRF5340, only the SoftDevice Controller is supported for Bluetooth® mesh.

Bluetooth direction finding

Antenna switching does not work on targets nrf5340dk_nrf5340_cpuapp and nrf5340dk_nrf5340__cpuapp_ns

Antenna switching does not work when direction finding sample applications are built for nrf5340dk_nrf5340_cpuapp and nrf5340dk_nrf5340_cpuapp_ns targets. That is caused by GPIO pins that are responsible for access to antenna switches, not being assigned to network core.


NCSDK-7173: nRF5340 network core bootloader cannot be built stand-alone

The nRF5340: Network core bootloader sample does not compile when built stand-alone. It compiles without problems when included as a child image.

Workaround: Include the nRF5340: Network core bootloader sample as child image instead of compiling it stand-alone.

Public keys revocation

Public keys are not revoked when subsequent keys are used.

Incompatibility with nRF51

The bootloader does not work properly on nRF51.

Immutable bootloader not supported in SES

Building and programming the immutable bootloader (see Secure bootloader chain) is not supported in SEGGER Embedded Studio.

Immutable bootloader board restrictions

The immutable bootloader can only be used with the following boards:

  • nrf52840_pca10056

  • nrf9160_pca10090

nRF Secure Immutable Bootloader and netboot can overwrite non-OTP provisioning data

In architectures that do not have OTP regions, b0 and b0n images incorrectly linked to the size of their container can overwrite provisioning partition data from their image sizes. Issue related to NCSDK-7982.

The combination of nRF Secure Immutable Bootloader and MCUboot fails to upgrade both the application and MCUboot

Due to a change in dependency handling in MCUboot, MCUboot does not read any update as a valid update. Issue related to NCSDK-8681.

Build system

NCSIDB-816: nanopb/protoc not specified correctly by the nRF Connect SDK Toolchain

The nRF Connect SDK Toolchain includes the nanopb/protoc tool when installed, but the path to the tool is not propagated correctly to the nRF Connect SDK build system.

** Workaround:** Locate the nanopb generator-bin directory in your nRF Connect SDK Toolchain and add its path to your system’s global path. This makes the protoc tool executable findable.

NCSDK-6117: Build configuration issues

The build configuration consisting of nRF Secure Immutable Bootloader, Secure Partition Manager, and application does not work.

Workaround: Either include MCUboot in the build or use MCUboot instead of the immutable bootloader.

NCSDK-10672: is not updated during build

In the configuration with MCUboot, the might not be properly updated after code or configuration changes, because of missing dependencies.

Workaround: Clear the build if is going to be released to make sure that it is up to date.

NCSDK-6898: Overriding child images

Adding child image overlay from the CMakeLists.txt top-level file located in the samples directory overrides the existing child image overlay.

Workaround: Apply the configuration from the overlay to the child image manually.

NCSDK-6777: Project out of date when CONFIG_SECURE_BOOT is set

The DFU .zip file is regenerated even when no changes are made to the files it depends on. As a consequence, SES displays a “Project out of date” message even when the project is not out of date.

Workaround: Apply the fix from sdk-nrf PR #3241.

NCSDK-6848: MCUboot must be built from source when included



KRKNWK-7827: Application build system is not aware of the settings partition

The application build system is not aware of partitions, including the settings partition, which can result in application code overlapping with other partitions. As a consequence, writing to overlapping partitions might remove or damage parts of the firmware, which can lead to errors that are difficult to debug.

Workaround: Define and use a code partition to shrink the effective flash memory available for the application. You can use one of the following solutions:

Flash commands only program one core

west flash and ninja flash only program one core, even if multiple cores are included in the build.

Workaround: Execute the flash command from inside the build directory of the child image that is placed on the other core (for example, build/hci_rpmsg).

NCSDK-11234: Statically defined “pcd_sram” partition may cause ARM usage fault

Inconsistency between SRAM memory partitions in Partition Manager and DTS could lead to improper memory usage. For example, one SRAM region may be used for multiple purposes at the same time.

Workaround: Ensure that partitions defined by DTS and Partition Manager are consistent.

NCSDK-7982: Partition manager: Incorrect partition size linkage from name conflict

The partition manager will incorrectly link a partition’s size to the size of its container if the container partition’s name matches its child image’s name in CMakeLists.txt. This can cause the inappropriately-sized partition to overwrite another partition beyond its intended boundary.

Workaround: Rename the container partitions in the pm.yml and pm_static.yml files to something that does not match the child images’ names, and rename the child images’ main image partition to its name in CMakeLists.txt.


NCSDK-18357: Serial recovery does not work on nRF5340 network core

If a network core serial recovery is attempted using MCUboot serial recovery, the upload will complete, but the image will not be transferred to the network core and the upgrade will fail.

NCSDK-18422: Serial recovery fails to write to slots in QSPI

If a slot resides in an external QSPI storage area and this area is written to in MCUboot’s serial recovery system, the writing will not work due to memory buffer alignment offsets and requirements with the underlying flash driver.

NCSDK-18108: s1 variant image configuration mismatch

If an image with an s1 variant is configured and the s0 image configuration is changed using menuconfig, these changes will not be reflected in the s1 configuration, which can lead to a differing build configuration or the build does not upgrade.

NCSDK-11308: Powering off device immediately after serial recovery of the nRF53 network core firmware results in broken firmware

The network core will not be able to boot if the device is powered off too soon after completing a serial recovery update procedure of the network core firmware. This is because the firmware is being copied from shared RAM to network core flash after mcumgr indicates that the serial recovery procedure has completed.

Workaround: Use one of the following workarounds:

  • Wait for 30 seconds before powering off the device after performing serial recovery of the nRF53 network core firmware.

  • Re-upload the network core firmware with a new serial recovery procedure if the device was powered off too soon in a previous procedure.

NCSDK-6238: Socket API calls may hang when using Download client

When using the Download client library with HTTP (without TLS), the application might not process incoming fragments fast enough, which can starve the Modem library buffers and make calls to the Modem library hang. Samples and applications that are affected include those that use Download client to download files through HTTP, or those that use FOTA download with modem updates enabled.


Jobs not received after reset

When using AWS FOTA, no new jobs are received on the device if the device is reset during a firmware upgrade or loses the MQTT connection.

Workaround: Delete the stalled in progress job from AWS IoT.

Stalled download

FOTA download does not resume a download if the device loses the connection.

Workaround: Call fota_download_start() again with the same arguments when the connection is re-established to resume the download.

Offset not retained with an MCUboot target

When using the MCUboot target in DFU target, the write/downloaded offset is not retained when the device is reset.

Download stopped on socket connection timeout

In the nRF9160: AWS FOTA and nRF9160: HTTP application update samples, the download is stopped if the socket connection times out before the modem can delete the modem firmware. A fix for this issue is available in commit 38625ba7.

Workaround: Call fota_download_start() again with the same arguments.

Update event triggered by an error event

If the last fragment of a FOTA download is received but is corrupted, or if the last write is unsuccessful, the library emits an error event as expected. However, it also emits an apply/request update event, even though the downloaded data is invalid.

FW upgrade is broken for multi-image builds

Firmware upgrade using mcumgr or USB DFU is broken for multi-image builds, because the devicetree configuration is not used. Therefore, it is not possible to upload the image.

Workaround: Build MCUboot and the application separately.


Sample incompatibility with the nRF5340 PDK

The NFC: TNEP poller and NFC: Tag reader samples cannot be run on the nRF5340 PDK. There is an incorrect number of pins defined in the MDK files, and the pins required for NFC Reader ST25R3911B cannot be configured properly.

Unstable NFC tag samples

NFC tag samples are unstable when exhaustively tested (performing many repeated read and/or write operations). NFC tag data might be corrupted.

Secure Partition Manager (SPM)


As of the nRF Connect SDK v2.1.0, Secure Partition Manager (SPM) is deprecated and replaced by Trusted Firmware-M (TF-M).

NCSIDB-114: Default logging causes crash

Enabling default logging in the Secure Partition Manager sample makes it crash if the sample logs any data after the application has booted (for example, during a SecureFault, or in a secure service). At that point, RTC1 and UARTE0 are non-secure.

Workaround: Do not enable logging and add a breakpoint in the fault handling, or try a different logging backend.

NCSDK-8232: Secure Partition Manager and application building together

It is not possible to build and program Secure Partition Manager and the application individually.

CIA-248: Samples with default SPM config fails to build for thingy91_nrf9160_ns

All samples using the default SPM config fails to build for the thingy91_nrf9160_ns build target if the sample is not set up with MCUboot.

Workaround: Use the main branch.


NCSDK-15494: Unable to build with RSA and ECIES-X25519 image encryptions

Building MCUboot with either RSA or ECIES-X25519 image encryptions feature enabled is not possible.

Workaround: To fix the issue, update the sdk-mcuboot repository by cherry-picking the upstream commits with the following hashes: 7315e424b91503819307d33ebbc3140103470dd8 and 0f7db390d3537bff0feee20f900f9720f90f33f9.

Recovery with the USB does not work

The MCUboot recovery feature using the USB interface does not work.



NCSDK-15697: ECDH key generation for Curve25519 is failing with the legacy Mbed TLS APIs for CryptoCell

This only affects the functions mbedtls_ecdh_make_params_edwards and mbedtls_ecdh_read_params_edwards.

NCSDK-13843: Limited support for MAC in PSA Crypto APIs

The provided message authentication codes (MAC) implementation in the PSA Crypto APIs has limited support in accelerators. Only the CryptoCell accelerator supports MAC operations in PSA Crypto APIs and the supported hash algorithms are SHA-1/SHA-224/SHA-256.

NCSDK-13843: Limited support for key derivation in PSA Crypto APIs

The provided key derivation implementation in the PSA Crypto APIs has limited support in accelerators. Only the CryptoCell accelerator supports key derivation in PSA Crypto APIs and the supported hash algorithms are the SHA-1/SHA-224/SHA-256.

NCSDK-13842: Limited ECC support in PSA Crypto APIs

The provided ECDSA implementation in the CryptoCell accelerator does not support 521 bit curves.

NCSDK-13825: Mbed TLS legacy APIs from Oberon has limited TLS/DTLS support

The legacy Mbed TLS APIs in Oberon for TLS/DTLS do not support the RSA and DHE algorithms.

NCSDK-13841: Limited support for RSA in PSA Crypto APIs

The provided RSA implementation in the PSA Crypto APIs has limited support in accelerators. Only the CryptoCell accelerator supports RSA in PSA Crypto APIs. Currently, the only supported mode is PKCS1-v1.5. The key size needs to be smaller than 2048 bits and the supported hash functions are SHA-1/SHA-224/SHA-256.

NCSDK-13844: Limited support for GCM in PSA Crypto APIs in Oberon

The provided GCM implementation of the PSA Crypto APIs in the Oberon accelerator only supports 12 bytes IV.

NCSDK-13900: Limited AES CBC PKCS7 support in PSA Crypto APIs

The provided implementation in the CryptoCell accelerator for AES CBC with PKCS7 padding does not support multipart APIs.

NCSDK-5883: CMAC behavior issues

CMAC glued with multiple backends may behave incorrectly due to memory allocation issues.

Workaround: Disable glued CMAC and use only one of the enabled backends.

NCSDK-5546: Oberon missing symbols for HKDF

nRF Oberon v3.0.5 is missing symbols for HKDF using SHA1, which will be fixed in an upcoming version of the library.

Workaround: Use a different backend (for example, vanilla Mbed TLS) for HKDF/HMAC using SHA1.

Limited support for Nordic Security Module

The Nordic Security Module is currently only fully supported on nRF52840 and nRF9160 devices. It gives compile errors on nRF52832, nRF52833, nRF52820, nRF52811, and nRF52810.

Workaround: To fix the errors, cherry-pick commits in nrfxlib PR #205.

Glue layer symbol renaming issue

The Nordic Security Module glue layer is broken because symbol renaming is not handled correctly. Therefore, the behavior is undefined when selecting multiple back-ends for the same algorithm (for example, AES).

GNSS sockets

Cold start and A-GPS data not supported

Forcing a cold start and writing A-GPS data is not yet supported.

Hard-fault with GPS in running mode

Implementation might hard-fault when GPS is in running mode and messages are not read fast enough.

NMEA strings might return wrong length

NMEA strings are valid c-strings (0-terminated), but the read function might return wrong length.

Closing sockets

Sockets can only be closed when GPS is in stopped mode. Moreover, closing a socket does not properly clean up all memory resources. If a socket is opened and closed multiple times, this might starve the system.

Multiprotocol Service Layer (MPSL)

DRGN-16642: If radio notifications on ACTIVE are used, MPSL might assert



MPSL requires RC clock calibration to be enabled when the RC clock is used as the Low Frequency clock source.

DRGN-14153: Radio Notification power performance penalty

The Radio Notification feature has a power performance penalty proportional to the notification distance. This means an additional average current consumption of about 600 µA for the duration of the radio notification.

KRKNWK-8842: MPSL does not support nRF21540 revision 1 or older

The nRF21540 revision 1 or older is not supported by MPSL. This also applies to kits that contain this device.

Workaround: Check the Nordic Semiconductor website for the latest information on availability of the product version of nRF21540.

DRGN-6362: Do not use the synthesized low frequency clock source

The synthesized low frequency clock source is neither tested nor intended for usage with MPSL.

NCSIDB-731: MPSL timeslot crashes when calling kernel APIs from zero latency interrupts

Calling kernel APIs is not allowed from zero latency interrupts.

DRGN-17014: High Frequency Clock staying active

The High Frequency Clock will stay active if it is turned on between timing events. This could occur during Low Frequency Clock calibration when using the RC oscillator as the Low Frequency Clock source.

DRGN-16506: Higher current consumption between timeslot events made with MPSL_TIMESLOT_HFCLK_CFG_NO_GUARANTEE

When timeslot requests are made with MPSL_TIMESLOT_HFCLK_CFG_NO_GUARANTEE, the current consumption between events is higher than expected.


DRGN-15223: CONFIG_SYSTEM_CLOCK_NO_WAIT is not supported for nRF5340

Using CONFIG_SYSTEM_CLOCK_NO_WAIT with nRF5340 devices might not work as expected.

DRGN-15176: CONFIG_SYSTEM_CLOCK_NO_WAIT is ignored when Low Frequency Clock is started before initializing MPSL

If the application starts the Low Frequency Clock before calling mpsl_init(), the clock configuration option CONFIG_SYSTEM_CLOCK_NO_WAIT has no effect. MPSL will wait for the Low Frequency Clock to start.

Workaround: When CONFIG_SYSTEM_CLOCK_NO_WAIT is set, do not start the Low Frequency Clock.

DRGN-15064: External Full swing and External Low swing not working

Even though the MPSL Clock driver accepts a Low Frequency Clock source configuration for External Full swing and External Low swing, the clock control system is not configured correctly. For this reason, do not use CLOCK_CONTROL_NRF_K32SRC_EXT_FULL_SWING and CLOCK_CONTROL_NRF_K32SRC_EXT_LOW_SWING.

DRGN-11059: Front-end module API not implemented for SoftDevice Controller

Front-end module API is currently not implemented for SoftDevice Controller. It is only available for 802.15.4.

802.15.4 Radio driver

In addition to the known issues listed here, see also 802.15.4 Radio driver limitations for permanent limitations.

KRKNWK-14950: MPSL asserts during operation with heavy load

An operation under heavy load can end with a crash, with the MPSL message ASSERT: 108, 659. This issue was observed very rarely during stress tests on the devices from the nRF53 and nRF52 Series.

KRKNWK-14898: CSMA-CA backoff parameters might not be randomized in an uniform way

The backoff parameters of the CSMA-CA operation are generated by the logic which might not return the uniformly distributed random numbers.

KRKNWK-11384: Assertion with Bluetooth® LE and multiprotocol usage

The device might assert on rare occasions during the use of Bluetooth® LE and 802.15.4 multiprotocol.

KRKNWK-8133: CSMA-CA issues

Using CSMA-CA with the open-source variant of the 802.15.4 Service Layer (SL) library causes an assertion fault. CSMA-CA support is currently not available in the open-source SL library.

KRKNWK-6255: RSSI parameter adjustment is not applied

The RADIO: RSSI parameter adjustment errata (153 for nRF52840, 225 for nRF52833 and nRF52820, 87 for nRF5340) are not applied for RSSI, LQI, Energy Detection, and CCA values used by the 802.15.4 protocol. There is an expected offset up to +/- 6 dB in extreme temperatures of values based on RSSI measurement.

Workaround: To apply RSSI parameter adjustments, cherry-pick the commits in hal_nordic PR #88, sdk-nrfxlib PR #381, and sdk-zephyr PR #430.

SoftDevice Controller

In addition to the known issues listed here, see also Limitations for permanent limitations.

DRGN-16013: Initiating connections over extended advertising is not supported when external radio coexistence and FEM support are enabled

The initiator can assert when initiating a connection to an extended advertiser when both external radio coexistence and FEM are enabled.

Workaround: Do not enable both coex (CONFIG_MPSL_CX_BT) and FEM (CONFIG_MPSL_FEM) when support for extended advertising packets is enabled (CONFIG_BT_EXT_ADV).

DRGN-17656: Hard fault with periodic advertising synchronization

When creating a periodic advertising synchronization, a hard fault might occur if receiving legacy advertising PDUs.

DRGN-17454: Wrong data length is selected if the even length is greater than 65535 us

If the event length (CONFIG_BT_CTLR_SDC_MAX_CONN_EVENT_LEN_DEFAULT) was set to a value greater than 65535 us, the auto-selected maximum data length was set to 27 bytes due to an integer overflow.

DRGN-17651: Incorrect memory usage if configuring fewer TX/RX buffers than the default value

When using the memory macros with less TX/RX packet count than the default value, the actual memory usage might be higher than expected.

DRGN-15903: BT_CTLR_TX_PWR is ignored by the SoftDevice Controller

Using BT_CTLR_TX_PWR does not set TX power.

Workaround: Use the HCI command Zephyr Write Tx Power Level to dynamically set TX power.

DRGN-17710: Periodic advertiser delay

The periodic advertiser sends its AUX_SYNC_IND packet 40 us later than the one indicated in the SyncInfo of the AUX_ADV_IND packet.

DRGN-17710: Scanner packet reception delay

The scanner attempts to receive the first AUX_SYNC_IND packet 40 us later than the one indicated in the SyncInfo of the AUX_ADV_IND. This may result in the device failing to establish a synchronization to the periodic advertiser.

DRGN-17110: Wrong address type in the LE Periodic Advertising Sync Established event when the Periodic Advertiser List is used to establish a synchronization

The SoftDevice Controller sometimes does not set the address type when the Periodic Advertiser List is used to establish a synchronization to a Periodic Advertiser.

DRGN-17110: The Advertiser Address Type in the LE Periodic Advertising Sync Established event is not set to 0x02 or 0x03, even if the advertiser’s address was resolved (DRGN-17110)

In the case the address is resolved, the reported address type is still set to 0x00 or 0x01.

DRGN-16859: The vendor-specific HCI commands Zephyr Write TX Power Level and Zephyr Read TX Power Level may return “Unknown Advertiser Identifier (0x42)” when setting advertising output power

The SoftDevice Controller will return this error code if the command is issued before advertising parameters are set.

Workaround: Configure the advertiser before setting TX Power using HCI LE Set Advertising Parameters

DRGN-16808: Assertion on nRF53 Series devices when the RC oscillator is used as the Low Frequency clock source

The SoftDevice Controller might assert when CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC is set on nRF53 Series devices and the device is connected as a peripheral.

Workaround: Do not use the RC oscillator as the Low Frequency clock source.

DRGN-16650: Undefined behavior when extended scanning is enabled

When extended scanning is enabled and CONFIG_BT_BUF_ACL_RX_SIZE is set to a value less than 251, it may result in asserts or undefined behavior.

Workaround: Set CONFIG_BT_BUF_EVT_RX_SIZE to 255 when extended scanning is enabled.

DRGN-16394: The host callback provided to sdc_enable() is always called after every advertising event

This will cause slightly increased power consumption.

DRGN-16394: The peripheral accepts a channel map where all channels are marked as bad

If the initiator sends a connection request with all channels marked as bad, the peripheral will always listen on data channel 0.

DRGN-16317: The SoftDevice Controller may discard LE Extended Advertising Reports

If there is insufficient memory available or the Host is not able to process HCI events in time, the SoftDevice Controller can discard LE Extended Advertising Reports. If advertising data is split across multiple reports and any of these are discarded, the Host will not be able to reassemble the data.

Workaround: Increase CONFIG_BT_BUF_EVT_RX_COUNT until events are no longer discarded.

DRGN-16341: The SoftDevice Controller may discard LE Extended Advertising Reports

Extended Advertising Reports with data length of 228 are discarded.

DRGN-16113: Active scanner assert when performing extended scanning

The active scanner might assert when performing extended scanning on Coded PHY with a full whitelist.

Workaround: On nRF52 series devices, do not use coex and fem. On nRF53 series devices, do not use CODED PHY.

DRGN-16079: LLPM mode assertion

An assertion can happen when in the LLPM mode and the connection interval is more than 1 ms.

Workaround: Only use 1 ms connection interval when in LLPM mode.

DRGN-15993: Assertion with legacy advertising commands

An assertion can happen when using legacy advertising commands after HCI LE Clear Advertising Sets.

Workaround: Do not mix legacy and extended advertising HCI commands.

DRGN-15852: In rare cases on nRF53 Series devices, an assert can occur while scanning

This only occurs when the host started scanning using HCI LE Set Scan Enable. This is default configuration of the Bluetooth® host.

Workaround: Use extended scanning commands. That is, set CONFIG_BT_EXT_ADV to use HCI LE Set Extended Scan Enable instead.

DRGN-15852: In rare cases on nRF53 Series, the scanner generates corrupted advertising reports

The following fields are affected:

  • Event_Type

  • Address_Type

  • Direct_Address_Type

  • TX_Power

  • Advertising_SID

DRGN-15586: “HCI LE Set Scan Parameters” accepts a scan window greater than the scan interval

This can result in undefined behavior. It should fail with the result “Invalid HCI Command Parameters (0x12)”.

Workaround: The application should make sure the scan window is set to less than or equal to the scan interval.

DRGN-15547: Assertion when updating PHY and the event length is configured too low

The SoftDevice Controller may assert if:

  • sdc_cfg_t with event_length is set to less than 2500 us and the PHY is updated from 2M to 1M, or from either 1M or 2M to Coded PHY.

  • sdc_cfg_t with event_length is set to less than 7500 us and a PHY update to Coded PHY is performed.

The default value of CONFIG_SDC_MAX_CONN_EVENT_LEN_DEFAULT is 7500 us.
The minimum event length supported by CONFIG_SDC_MAX_CONN_EVENT_LEN_DEFAULT is 2500 us.
  • Set sdc_cfg_t with event_length to at least 2500 us if the application is using 1M PHY.

  • Set sdc_cfg_t with event_length to at least 7500 us if the application is using Coded PHY.

DRGN-13594: The channel map provided by the LE Host Set Channel Classification HCI command is not always applied on the secondary advertising channels

In this case, the extended advertiser can send secondary advertising packets on channels which are disabled by the Host.

DRGN-15338: Extended scanner may generate reports containing truncated data from chained advertising PDUs

The scanner reports partial data from advertising PDUs when there is not enough storage space for the full report.

DRGN-15469: Slave connections can disconnect prematurely if there are scheduling conflicts with other roles

This is more likely to occur during long-running events such as flash operations.

DRGN-15369: Radio output power cannot be set using the vendor-specific HCI command Zephyr Write TX Power Level for all power levels

The command returns “Unsupported Feature or Parameter value (0x11)” if the chosen power level is not supported by the used hardware platform.

Workaround: Only select output power levels that are supported by the hardware platform.

DRGN-15694: An assert can occur when running an extended advertiser with maximum data length and minimum interval on Coded PHY

The assert only occurs if there are scheduling conflicts.

Workaround: Ensure the advertising interval is configured to at least 30 milliseconds when advertising on LE Coded PHY.

DRGN-15484: A connectable or scannable advertiser may end with sending a packet without listening for the CONNECT_IND, AUX_CONNECT_REQ, SCAN_REQ, or AUX_SCAN_REQ

These packets sent by the scanner or initiator can end up ignored in some cases.

DRGN-15531: The coding scheme provided by the LE Set PHY HCI Command is ignored after a remote initiated PHY procedure

The PHY options set by the host in LE Set PHY command are reverted when the remote initiates a PHY update. This happens because of the automatic reply of a PHY update Request in the SoftDevice Controller. This makes it impossible to change the PHY preferred coding in both directions. When receiving on S2, the SoftDevice Controller will always transmit on S8 even when configured to prefer S2.

DRGN-15758: The controller may still have pending events after sdc_hci_evt_get() returns false

This will only occur if the host has masked out events.

DRGN-15251: Very rare assertion fault when connected as peripheral on Coded PHY

The controller might assert when the following conditions are met:

  • The device is connected as a peripheral.

  • The connection PHY is set to LE Coded PHY.

  • The devices have performed a data length update, and the supported values are above the minimum specification defined values.

  • A packet is received with a CRC error.

Workaround: Do not enable CONFIG_BT_DATA_LEN_UPDATE for applications that require Coded PHY as a peripheral device.

DRGN-15310: HCI Read RSSI fails

The command “HCI Read RSSI” always returns “Command Disallowed (0x0C)”.

DRGN-15465: Corrupted advertising data when CONFIG_BT_EXT_ADV is set

Setting scan response data for a legacy advertiser on a build with extended advertising support corrupts parts of the advertising data. When using BT_LE_ADV_OPT_USE_NAME (which is the default configuration in most samples), the device name is put in the scan response. This corrupts the advertising data.

Workaround: Do not set scan response data. That implies not using the BT_LE_ADV_OPT_USE_NAME option, or the BT_LE_ADV_CONN_NAME macro when initializing Bluetooth. Instead, use BT_LE_ADV_CONN, and if necessary set the device name in the advertising data manually.

DRGN-15475: Samples might not initialize the SoftDevice Controller HCI driver correctly

Samples using both the advertising and the scanning state, but not the connected state, fail to initialize the SoftDevice Controller HCI driver. As a result, the function bt_enable() returns an error code.

Workaround: Manually enable CONFIG_SOFTDEVICE_CONTROLLER_MULTIROLE for the project configuration.

DRGN-15382: The SoftDevice Controller cannot be qualified on nRF52832

The SoftDevice Controller cannot be qualified on nRF52832.

Workaround: Upgrade to v1.5.1 or use the main branch.

DRGN-14008: The advertising data is cleared every time the advertising set is configured

This causes the “HCI LE Set Extended Advertising Parameters” command to accept data which cannot be fit within the advertising interval instead of returning “Packet Too Long (0x45)”. This would only occur if the advertising set is configured to use maximum data length on LE Coded PHY with an advertising interval less than 30 milliseconds.

DRGN-15291: The generation of QoS Connection events is not disabled after an HCI reset

Some event reports may still occur after a reset.

DRGN-15226: Link disconnects with reason “LMP Response Timeout (0x22)”

If the slave receives an encryption request while the “HCI LE Long Term Key Request” event is disabled, the link disconnects with the reason “LMP Response Timeout (0x22)”. The event is disabled when CONFIG_BT_SMP and/or CONFIG_BT_CTLR_LE_ENC is disabled.

DRGN-11963: LL control procedures cannot be initiated at the same time

The LL control procedures (LE start encryption and LE connection parameter update) cannot be initiated at the same time or more than once. The controller will return an HCI error code “Controller Busy (0x3a)”, as per specification’s chapter 2.55.

Workaround: Do not initiate these procedures at the same time.

DRGN-13921: Directed advertising issues using RPA in TargetA

The SoftDevice Controller will generate a resolvable address for the TargetA field in directed advertisements if the target device address is in the resolving list with a non-zero IRK, even if privacy is not enabled and the local device address is set to a public address.

Workaround: Remove the device address from the resolving list.

DRGN-10367: Advertiser times out earlier than expected

If an extended advertiser is configured with limited duration, it will time out after the first primary channel packet in the last advertising event.

DRGN-11222: A Central may disconnect prematurely if there are scheduling conflicts while doing a control procedure with an instant

This bug will only be triggered in extremely rare cases.

DRGN-13231: A control packet may be sent twice even after the packet is ACKed

This only occurs if the radio is forced off due to an unforeseen condition.

DRGN-13350: HCI LE Set Extended Scan Enable returns “Unsupported Feature or Parameter value (0x11)”

This occurs when duplicate filtering is enabled.

Workaround: Do not enable duplicate filtering in the controller.

DRGN-12122: secondary_max_skip cannot be set to a non-zero value

HCI LE Set Advertising Parameters will return “Unsupported Feature or Parameter value (0x11)” when secondary_max_skip is set to a non-zero value.

DRGN-13079: An assert occurs when setting a secondary PHY to 0 when using HCI LE Set Extended Advertising Parameters

This issue occurs when the advertising type is set to legacy advertising.

CONFIG_BT_HCI_TX_STACK_SIZE requires specific value

CONFIG_BT_HCI_TX_STACK_SIZE must be set to 1536 when selecting CONFIG_BT_LL_SOFTDEVICE.


CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE must be set to 2048 when selecting CONFIG_BT_LL_SOFTDEVICE on Bluetooth: Central UART and Bluetooth: Central BAS.

CONFIG_NFCT_IRQ_PRIORITY requires specific value

CONFIG_NFCT_IRQ_PRIORITY must be set to 5 or less when selecting CONFIG_BT_LL_SOFTDEVICE on Bluetooth: Peripheral HIDS keyboard.

Several issues for nRF5340

The following issues can occur when using SoftDevice Controller with nRF5340:

  • Poor performance when performing active scanning.

  • The controller could assert when receiving extended advertising packets.

  • The T_IFS could in certain conditions be off by 5 us.

  • The radio could stay in the TX state longer than expected. This issue can only occur when sending a packet on either LE 1M or LE 2M PHY after receiving or transmitting a packet on LE Coded PHY. If this occurs while performing a Link Layer Control Procedure, the controller could end up retransmitting an acknowledged packet, resulting in a disconnect.

Sending control packet twice

A control packet could be sent twice even after the packet was acknowledged. This would only occur if the radio was forced off due to an unforeseen condition.

DRGN-13029: The application will not immediately restart a connectable advertiser after a high duty cycle advertiser times out

In some cases, the host may restart advertising sooner than the SoftDevice Controller is able to free its connection context.

Workaround: Wait 500 ms before restarting a connectable advertiser

Assert risk after performing a DLE procedure

The controller could assert when receiving a packet with a CRC error on LE Coded PHY after performing a DLE procedure where RX Octets is changed to a value above 140.

No data issue when connected to multiple devices

hci_data_get() may return “No data available” when there is data available. This issue will only occur when connected to multiple devices at the same time.

Assert on LE Write Suggested Default Data Length

The controller will assert if the host issues LE Write Suggested Default Data Length.

HCI LE Set Privacy Mode appears as not supported

The controller does not indicate support for HCI LE Set Privacy Mode although it is supported.

Assert if advertising data is set after HCI Reset

The controller will assert if advertising data is set after HCI Reset without first setting advertising parameters.

Assert on writing to flash

The controller may assert when writing to flash.

Timeout without sending packet

A directed advertiser may time out without sending a packet on air.



Incorrect pin definition for nRF5340

For nRF5340, the pins P1.12 to P1.15 are unavailable due to an incorrect pin number definition in the MDK.

nrfx_saadc driver

Samples might be swapped

Samples might be swapped when buffer is set after starting the sample process, when more than one channel is sampled. This can happen when the sample task is connected using PPI and setting buffers and sampling are not synchronized.

nrfx_uarte driver

RX and TX not disabled in uninit

The driver does not disable RX and TX in uninit, which can cause higher power consumption.

nrfx_uart driver

tx_buffer_length set incorrectly

The nrfx_uart driver might incorrectly set the internal tx_buffer_length variable when high optimization level is set during compilation.

Trusted Firmware-M (TF-M)

NCSDK-15909: TF-M may fail to build due to flash overflow with Zephyr SDK 0.14.2


Workaround: Use one of the following workarounds:

NCSDK-16916: TF-M non-secure storage size may be incorrect when having multiple storage partitions

TF-M non-secure storage partition nonsecure_storage size is incorrectly calculated when it has multiple storage partitions inside.

Workaround: Use one of the following workarounds:

TF-M is not supported for Thingy:91 v1.5.0 and lower versions

TF-M does not support Thingy:91 v1.5.0 and lower versions when using the factory-programmed bootloader to upgrade the firmware. TF-M is compatible with all versions of the Thingy:91 if you first upgrade the bootloader using an external debug probe. Additionally, TF-M functions while using the bootloader to upgrade the firmware if you upgrade the bootloader to nRF Connect SDK v2.0.0.

NCSDK-15382: TF-M uses more RAM compared to SPM in the minimal configuration

TF-M uses 64 KB of RAM in the minimal configuration, while SPM uses 32 KB of RAM.

Workaround: Free up memory in the application if needed or keep CONFIG_SPM enabled in the application.

NCSDK-15379: TF-M does not support FP Hard ABI

TF-M does not support enabling the Float Point Hard Application Binary Interface configuration enabled with CONFIG_FP_HARDABI.

Workaround: Use CONFIG_FP_SOFTABI or keep CONFIG_SPM enabled in the application.

NCSDK-15345: TF-M does not support non-secure partitions in external flash

TF-M does not support configuring a non-secure partition in external flash, such as non-secure storage or MCUboot secondary partition. Partitions that TF-M will attempt to configure as non-secure are: tfm_nonsecure, nonsecure_storage, and mcuboot_secondary.

Workaround: Do not put non-secure partitions in external flash or keep CONFIG_SPM enabled in the application.

NCSDK-12483: Missing debug symbols

Some debug symbols are missing sometimes.

Workaround: Add the text zephyr_link_libraries(-Wl,--undefined=my_missing_debug_symbol) in the application CMakeLists.txt file.

NCSDK-12342: SecureFault exception while accessing protected storage

When accessing protected storage, a SecureFault exception is sometimes triggered and execution halts.

NCSDK-11195: Build errors when enabling CONFIG_BUILD_WITH_TFM option

Configuring the BUILD_WITH_TFM configuration in SES project configuration or using west -t menuconfig results in build errors.

Workaround: Set CONFIG_BUILD_WITH_TFM=y in project configuration file (prj.conf) or through west command line (west build -- -DCONFIG_BUILD_WITH_TFM=y).

NCSDK-12306: Enabling debug configuration causes usage fault on nRF9160

When the debug configuration CONFIG_TFM_CMAKE_BUILD_TYPE_DEBUG is enabled, a usage fault is triggered during boot on nRF9160.

NCSDK-14590: Usage fault in interrupt handlers when using FPU extensions

When the ARM_NONSECURE_PREEMPTIBLE_SECURE_CALLS Kconfig option is disabled, a usage fault can be triggered when an interrupt handler uses FPU extensions while interrupting the secure processing environment.

Workaround: Do not disable the ARM_NONSECURE_PREEMPTIBLE_SECURE_CALLS option when the FPU option is enabled.

NCSDK-15443: TF-M cannot be booted by MCUboot without enabling CONFIG_MCUBOOT_CLEANUP_ARM_CORE in MCUboot

TF-M cannot be booted by MCUboot unless MCUboot cleans up the ARM hardware state to reset values before booting TF-M.

Workaround: Upgrade MCUboot with CONFIG_MCUBOOT_CLEANUP_ARM_CORE enabled or keep CONFIG_SPM enabled in the application.

NCSDK-13530: TF-M minimal build has increased in size

TF-M minimal build exceeds 32 kB due to increased dependencies in the TF-M crypto partition.

KRKNWK-12777: FLASHACCER event triggered after soft reset

After soft reset, TF-M sometimes triggers a FLASHACCERR event and execution halts.

NCSDK-14015: Execution halts during boot

When the CONFIG_RPMSG_SERVICE is enabled on the nRF5340 SoC together with TF-M, the firmware does not boot. This option is used by OpenThread and Bluetooth modules.

Workaround: Place the rpmsg_nrf53_sram partition inside the sram_nonsecure partition using Partition Manager.

NCSDK-13949: TF-M Secure Image copies FICR to RAM on nRF9160

TF-M Secure Image copies the FICR to RAM address between 0x2003E000 and 0x2003F000 during boot on nRF9160.


The time returned by clock_gettime() API becomes incorrect after one week of uptime

The time returned by POSIX clock_gettime() API becomes incorrect after one week elapses. This is due to an overflow in the uptime conversion.

NCSDK-6330: USB Mass Storage Sample Application fails MSC Tests from USB3CV test tool

USB Mass Storage Sample Application fails the USB3CV compliance Command Set Test from the MSC Tests suite.

NCSDK-6328: USB CDC ACM Composite Sample Application fails Chapter 9 Tests from USB3CV test tool

USB CDC ACM Sample Composite Application fails the USB3CV compliance TD 9.1: Device Descriptor Test from the Chapter 9 Test suite.

NCSDK-6331: WebUSB sample application fails Chapter 9 Tests from USB3CV test tool

WebUSB sample application fails the USB3CV compliance TD 9.21: LPM L1 Suspend Resume Test from the Chapter 9 Test suite.

NCSIDB-108: Thread context switch might lead to a kernel fault

If the Zephyr kernel preempts the current thread and performs a context switch to a new thread while the current thread is executing a secure service, the behavior is undefined and might lead to a kernel fault. To prevent this situation, a thread that aims to call a secure service must temporarily lock the kernel scheduler (k_sched_lock()) and unlock the scheduler (k_sched_unlock()) after returning from the secure call.

Counter Alarm sample does not work

The Counter Alarm Sample does not work. A fix can be found in Pull Request #16736.

USB Mass Storage Sample Application compilation issues

USB Mass Storage Sample Application does not compile.

NCSDK-6832: SMP Server sample fails upon initialization

The SMP Server Sample will fail upon initialization when using the bt-overlay.conf Kconfig overlay file. This happens because of a stack overflow.

Workaround: Set CONFIG_MAIN_STACK_SIZE to 2048.

SEGGER Embedded Studio Nordic Edition


SEGGER Embedded Studio Nordic Edition support has been deprecated with the nRF Connect SDK v2.0.0 release. Visual Studio Code is now the default IDE for the nRF Connect SDK. See the migrating from other IDEs to VS Code page in the Visual Studio Code documentation for information about how to migrate.

NCSDK-6852: Extra CMake options might not be applied in version 5.10d

If you specify Extra CMake Build Options in the Open nRF Connect SDK Project dialog and at the same time select an nRF Connect Toolchain Version of the form X.Y.Z, the additional CMake options are discarded.

Workaround: Select NONE (Use SES settings/environment PATH) from the nRF Connect Toolchain Version drop-down if you want to specify Extra CMake Build Options.

NCSDK-8372: Project name collision causes SES Nordic Edition to load the wrong project

Some samples that are located in different folders use the same project name. For example, there is a light_switch project both in the samples/bluetooth/mesh/ folder and in the samples/zigbee/ folder. When you select one of these samples from the project list in the Open nRF Connect SDK Project dialog, the wrong sample might be selected. Check the Build Directory field in the dialog to see if this is the case. The field indicates the path to the project that SES Nordic Edition will load.

Workaround: If the path in Build Directory points to the wrong project, select the correct project by using the button for Projects and navigating to the correct project location. The build directory will update automatically.

NCSDK-9992: Multiple extra CMake options applied as single option

If you specify two or more Extra CMake Build Options in the Open nRF Connect SDK Project dialog, those will be incorrectly treated as one option where the second option becomes a value to the first. For example: -DFOO=foo -DBAR=bar will define the CMake variable FOO having the value foo -DBAR=bar.

Workaround: Create a CMake preload script containing FOO and BAR settings, and then specify -C <pre-load-script>.cmake in Extra CMake Build Options.

In addition to these known issues, check the current issues in the official Zephyr repository, since these might apply to the nRF Connect SDK fork of the Zephyr repository as well. To get help and report issues that are not related to Zephyr but to the nRF Connect SDK, go to Nordic’s DevZone.