RE: Question about MCUboot version

jasr93 — Thu, 12 Feb 2026 11:14:20 GMT

Just one question related to this topic:

Every time we want to create an MCUBOOT update, we have to change SB_CONFIG_SECURE_BOOT_MCUBOOT_VERSION.

But what should we do with CONFIG_FW_INFO_FIRMWARE_VERSION within b0? b0 is immutable, so it can't be changed.

RE: Question about MCUboot version

Amanda Hsieh — Tue, 05 Nov 2024 16:09:46 GMT

Hi,

When MCUboot updates are enabled, the firmware embeds the nRF Secure Immutable Bootloader version using the CONFIG_FW_INFO_FIRMWARE_VERSION Kconfig option. However, during an update, MCUboot does not check this version; it only checks the MCUboot package version.

You can set the MCUboot update package version in sysbuild with SB_CONFIG_SECURE_BOOT_MCUBOOT_VERSION. You must increase this version number when deploying an MCUboot update. If the version in the update is lower than the current version, MCUboot will reject the update and not transfer it to the opposing secure boot firmware slot.

Using a VERSION file allows you to independently configure the version value for each build instance of the application.

See MCUboot update package version, Image versions, and Application version management.

Regards,
Amanda H.