FW version failure DFU OTA

[StephaneJ]

Hi,

I create my application image using nrfutil like this :

nrfutil pkg generate  --hw-version 52 --sd-req 0x00A8 --application-version 1 --application ../nRF5_SDK_15_0_0/examples/....../some_app.hex --key-file my_key.pem FW_image.zip

Everything was working great so far but for test purpose I added one argument to this line :

 --application-version-string "19.03.03"

I flashed my custom board with the nRF Toolbox app without issue, but now if I want to update my board again I should always add this argument to my nrfutil line. Otherwise I get the error :

FW version failure

How can I cancel this verification ?

Thanks

[StephaneJ]

I have wipe my board and completely reset BOOTLOADER and SOFTDEVICE then reuploaded an app image to reset the previous behavior.

But I'm still curious to know if there is a better solution.

[Vidar Berg]

Hi, 

The DFU verification logic in SDK 15.0.0 prohibits FW downgrades, so to "recover" the device you either need to wipe the settings page as you said, or change the verification mechanism to accept version downgrades.  SDK 15.3.0 has a configuration option in sdk_config.h to disable downgrade prevention.