nRF Connect SDK v3.4.2 Release Notes

nRF Connect SDK delivers reference software and supporting libraries for developing low-power wireless applications with Nordic Semiconductor products in the nRF52, nRF53, nRF54, nRF70, and nRF91 Series. The SDK includes open source projects (TF-M, MCUboot, OpenThread, Matter, and the Zephyr RTOS), which are continuously integrated and redistributed with the SDK.

Release notes might refer to “experimental” support for features, which indicates that the feature is incomplete in functionality or verification, and can be expected to change in future releases. To learn more, see Software maturity levels.

Highlights

This patch release adds the following changes on top of the nRF Connect SDK v3.4.1:

  • The nRF Connect SDK v3.4.2 is based on Zephyr 4.4.2, Mbed TLS 4.1.1, and TF-M 2.3.1.

    This patch release is part of the v3.4 release branch, which has long-term support (LTS) for five years from the v3.4.0 release. During this period, patch releases will provide updates for security vulnerabilities and critical bug fixes. These patch releases will not contain breaking changes unless security fixes require them.

  • The v3.4 release branch is the last nRF Connect SDK release branch that includes support for nRF52 Series devices. The nRF52 Series devices are considered feature complete, and support for them will be removed from samples and applications in the main branch.

Added the following supported features:

  • nRF54L Series:

    • Support for the nRF54LS05A and nRF54LS05B SoCs.

    • Support for the nRF54LV10A SoC.

Release tag

The release tag for the nRF Connect SDK manifest repository (https://github.com/nrfconnect/sdk-nrf) is v3.4.2. Check the west.yml file for the corresponding tags in the project repositories.

To use this release, check out the tag in the manifest repository and run west update. See Alternative method: Installing using command line and Updating the repositories for more information.

For information on the included repositories and revisions, see Repositories and revisions for v3.4.2.

IDE and tool support

nRF Connect extension for Visual Studio Code is the recommended IDE for nRF Connect SDK v3.4.2. See the Installation section for more information about supported operating systems and toolchain.

Supported modem firmware

See the following documentation for an overview of which modem firmware versions have been tested with this version of the nRF Connect SDK:

Use the latest version of the Programmer app of nRF Connect for Desktop to update the modem firmware. See Programming nRF91 Series DK firmware for instructions.

Known issues

Known issues are only tracked for the latest official release. See known issues for nRF Connect SDK v3.4.2 for the list of issues valid for the latest release.

Changelog

The following sections provide detailed lists of changes by component.

Bootloaders and DFU

  • Fixed:

    • An issue with signing MCUboot direct-XIP variant images, where sysbuild used the Zephyr signing path instead of the nRF Connect SDK signing script for the secondary slot image. Signed variant images could miss nRF Connect SDK-specific image metadata, such as the security counter or ROM-fixed flag, which caused the secondary slot image to be rejected unexpectedly.

    • A potential out-of-bounds access in application’s SMP. The image and slot indexes are now validated before use, and invalid inputs return safe fallback values.

IDE, OS, and tool support

Applications

This section provides detailed lists of changes by application.

Connectivity bridge

  • Fixed an issue on the Thingy:91 X where the CMSIS-DAP interface could not connect to the nRF91 Series SiP. The connection failed because the SiP was held in reset while the debug port was enabled.

Samples

This section provides detailed lists of changes by sample.

Bluetooth Fast Pair samples

Libraries

This section provides detailed lists of changes by library.

Binary libraries

Bluetooth libraries and services

  • Google Fast Pair Service (GFPS) library:

    • Fixed the validation of the Data Length parameter in requests that the Find Hub Network (FHN) extension receives on the Beacon Actions characteristic. Requests that declare a Data Length above the maximum supported value are now rejected with the Invalid Value error.

Modem libraries

  • SMS library:

    • Fixed an issue where the sms_register_listener() function returned a positive value instead of a negative error code when the modem responded with an AT error during SMS client registration. The function now returns -EFAULT in this case.

Libraries for networking

Other libraries

  • Date-Time library:

    • Fixed an issue where periodic time updates stopped permanently if the time was obtained, for example, from an %XTIME notification shortly before a scheduled update.

Integrations

This section provides detailed lists of changes by integration.

Memfault integration

MCUboot

The MCUboot fork in nRF Connect SDK (sdk-mcuboot) contains all commits from the upstream MCUboot repository up to and including 8d14eebfe0b7402ebdf77ce1b99ba1a3793670e9, with some nRF Connect SDK specific additions.

The code for integrating MCUboot into nRF Connect SDK is located in the ncs/nrf/modules/mcuboot folder.

The following list summarizes both the main changes inherited from upstream MCUboot and the main changes applied to the nRF Connect SDK specific additions:

  • Fixed:

    • An issue where MCUboot did not clear a serial recovery boot request after entering serial recovery when the CONFIG_NRF_BOOT_SERIAL_BOOT_REQ Kconfig option is enabled, causing the device to re-enter serial recovery on every reset instead of booting the application.

    • A bus fault in the custom type-length-value (TLV) validation hook when MCUboot runs in single-slot mode on the nRF54H20 SoC.

    • An issue where MCUboot did not validate image header size, image size, and protected TLV size against the boundaries of the flash partition that holds the installed image.

    • An issue where MCUboot serial recovery with progressive erase (CONFIG_BOOT_ERASE_PROGRESSIVELY) could erase the last image sector of a large upload when the image extended into the slot trailer area in external flash (for example, on the nRF54H20 SoC).

    • An issue where multi-image operation denied key revocation because the state check was done beyond the state table. This affected MCUboot instances that are used as a second-stage bootloader above nRF Secure Immutable Bootloader (NSIB) in the S0/S1 update scheme on nRF54L SoCs.

Zephyr

The Zephyr fork in nRF Connect SDK (sdk-zephyr) contains all commits from the upstream Zephyr repository up to and including dccb09599635bdff17633fa7e9dab014b91dce90 (Zephyr v4.4.2), with some nRF Connect SDK specific additions.

For the list of upstream Zephyr commits (not including cherry-picked commits) incorporated into nRF Connect SDK since v3.4.0, run the following command from the ncs/zephyr repository (after running west update):

git log --oneline dccb095996 ^684c9e8f32

For the list of nRF Connect SDK specific commits added since v3.4.0, including commits cherry-picked from upstream, run:

git log --oneline --cherry-pick --right-only ncs-v3.4.0...manifest-rev ^dccb095996

Documentation

  • Added the Open in VS Code button for each sample page. It lets you quickly open the sample and install the required version of the nRF Connect SDK toolchain.

  • Updated the Installing the nRF Connect SDK page by adding a button for installing the nRF Connect for VS Code with the latest stable release of the nRF Connect SDK. This has also simplified the structure of the page.