Debug secure bootloader shows invalid app while secure bootloader shows valid app after programming board

Question

Hi, 
 
 I'm working on modifying the secure bootloader (SDK 17, nRF52840, s140) to store the old app before the new app is programmed into Bank 0 (see this other thread ). Since I need to debug the bootloader, I need to use the debug bootloader ( pca10056_s140_ble_debug ) instead of the one I normally use ( pca10056_s140_ble ). The weird part is that when I program the "normal" bootloader + SoftDevice + Application, the app boots up fine after programming. However, when I program the debug bootloader + SoftDevice + Application, the bootloader does not recognize the app as valid and stays in DFU mode. 
 What could be the reason for this? I get no warnings or errors at compile time so I would say that the public key in the bootloader that is being used is the correct one as there is no other one. 
 
 Thanks in advance.

user4240 · Accepted Answer

Hi, 
 I'm surprised it says the settings page is invalid. The correct command for you SDK version should be (--app-boot-validation defaults to VALIDATE_GENERATED_CRC anyway): nrfutil settings generate --family NRF52840 --application $(OUTPUT_DIRECTORY)/nrf52840_xxaa.hex --application-version 1 --bootloader-version 1 --bl-settings-version 2 settings.hex 
 Here i omitted the --no-backup argument and set the settings version to '2' as required for this SDK version you are using. 
 Could you please try with the command above again and program the settings.hex with the nrfjprog command below? 
 $ nrfjprog --program settings.hex --sectorerase -r

Debug secure bootloader shows invalid app while secure bootloader shows valid app after programming board

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