DevAcademy - nRF Connect SDK Intermediate - Lesson 9 Exercise 5 - Unable to find bootable image

[Ken Yoshioka]

The solution for "nRF Connect SDK Intermediate - Lesson 9 Exercise 5" does not appear to boot-up after flashing and gives the following output on the com port:

*** Booting MCUboot v2.1.0-dev-9b4ae4cbc9e2 ***
*** Using nRF Connect SDK v3.1.1-e2a97fe2578a ***
*** Using Zephyr OS v4.1.99-ff8f0c579eeb ***
W: Failed reading sectors; BOOT_MAX_IMG_SECTORS=128 - too small?
E: Image in the primary slot is not valid!
E: Unable to find bootable image

It worked fine on nRF54L15-DK, but it's not working on the nRF54LM20-DK.

Here is my set-up:

• Hardware:  nRF54LM20-DK

• nRF Connect SDK: v3.1.1

• nRF Connect Toolchain: v3.1.1

• nRF Connect for VS Code: 2025.9.798

[Menon]

Hello,

Please note that the DevAcademy sample you are trying to use is not supported on the nRF54LM20-DK. This is fairly new hardware, and support for this DK has not yet been added to the Academy sample. I can try it on my side tomorrow and update you.

Kind regards,
Abhijith

[Ken Yoshioka]

Thank you for looking into this.

I am just attempting to verify the method for doing OTA over BLE with nRF54LM20-DK.

If you have another example that can do this, please let me know.

I have checked with_mcuboot and locator_tag example, and those appear to boot correctly with nRF54LM20-DK. But I'm not sure why those work but the example code does not.