[NCS 3.2.1-SINGLE SLOT DFU] Issue with nrf54L15dk

RE: [NCS 3.2.1-SINGLE SLOT DFU] Issue with nrf54L15dk

Amanda Hsieh — Thu, 05 Feb 2026 16:26:58 GMT

The nRF Connect for VS Code extension would wrap the nRF util commands.

RE: [NCS 3.2.1-SINGLE SLOT DFU] Issue with nrf54L15dk

longo92 — Thu, 05 Feb 2026 16:06:24 GMT

Ok, but how does the VS Code extension recognize that the key file also needs to be provisioned when you click the Flash command?

RE: [NCS 3.2.1-SINGLE SLOT DFU] Issue with nrf54L15dk

Amanda Hsieh — Thu, 05 Feb 2026 16:04:16 GMT

[quote user="longo92"]Is there a way to use a single command to both flash the .hex file and provision the key file[/quote]

Currently, there is no such command to achieve that.

RE: [NCS 3.2.1-SINGLE SLOT DFU] Issue with nrf54L15dk

longo92 — Thu, 05 Feb 2026 15:29:07 GMT

Yes, I am using the Programmer desktop application.

By the way, I need to set up a flashing script using the nrfutil device command. Is there a way to use a single command to both flash the .hex file and provision the key file, or do these need to be done as two separate commands?

RE: [NCS 3.2.1-SINGLE SLOT DFU] Issue with nrf54L15dk

Amanda Hsieh — Thu, 05 Feb 2026 15:23:04 GMT

Hi Alessandro,

[quote user=""]After flashing the merged.hex file generated in the build folder, the board appears to be unresponsive. [/quote]

How do you build and flash the image? Could you try to use VS Code to build and flash?

Guess you are not using VS Code to flash and only program the merged.hex on nRF5415L15DK. If so, you also need to provision keyfile.json under the build folder because this sample is enabled with MCUBOOT_GENERATE_DEFAULT_KMU_KEYFILE. See the explanation in this doc: Alternative provisioning method during development.

You can use nrfutil device x-provision-keys command to provision keys onto the KMU. See Provisioning keys to the board with the nRF Util tab.

I can reproduce the issue by programming the merged.hex on nRF5415L15DK via nRF Programmer, and also fix it by provisioning the keys with the following command:

PS C:\NCS\v3.2.1\nrf\samples\dfu\single_slot> nrfutil device x-provision-keys --key-file ./build/keyfile.json

If you use VS Code to flash, it would flash both the merged.hex and key file. See the log:

[quote user="longo92"]Could you please consider adding a note about this to the example’s README.rst? I think it would be very helpful for developers who are new to the nRF54 series.[/quote]

See the note in FOTA updates on nRF54L Series devices.

Regards,
Amanda H.

RE: [NCS 3.2.1-SINGLE SLOT DFU] Issue with nrf54L15dk

longo92 — Thu, 05 Feb 2026 14:57:48 GMT

Ok, I managed to get it working. The issue was that the public key was not updated.

We mainly work with the nRF52 series, where the public key is embedded together with MCUboot. In this example, however, the KMU is used, so the public key must be provisioned separately.

After following the KMU provisioning procedure described here:
docs.nordicsemi.com/.../kmu_provision.html

and provisioning the key using:

nrfutil device x-provision-keys --traits jlink --key-file .\build\keyfile.json

the issue was resolved.

Could you please consider adding a note about this to the example’s README.rst? I think it would be very helpful for developers who are new to the nRF54 series.

Best regards,
Alessandro