SDK12 DFU service not found

[jpolvi]

I am developing software for a custom hardware based on NRF52. Previously I was tasked on updating the old NRF51 based software (used on older version of the device) for NRF52 using SDK11. Once that was done my next task was updating the software for SDK12. The software is otherwise working fine but I am having problems with DFU. I tried creating a zip of the application and flashed the combined softdevice/bootloader from SDK12 examples folder (dfu/ble_dfu_send_hex) to the device. The device shows as DfuTest on the mobile DFU app but when I try to upload the zip all I get is "DFU service not found". I also tried compiling the secure DFU bootloader example and using that instead but the result is the same.

Do I need to also have DFU support in the application for that to work ? Currently the application has some kind of DFU functionality from the earlier SDK 11 implementation but I'm guessing that wont work. Any examples to study so that I can implement the functionality ?

[jpolvi]

I did some examination. It seems that the hex file containing both softdevice and bootloader is somehow broken (or possibly incompatible with the mobile application). If I upload that to the device and use nRF Connect on mobile it shows "Unknown service", but if I upload the relevant hex from SDK 11 the DFU is shown just fine ("Device Firmware Update Service"). Perhaps the mobile app is incompatible with the new SDK and must be updated ?

update: it seems old version was indeed the problem. I updated both NRF Connect and NRF toolbox and the unit now shows up as it should (and the service is also shown as "Secure DFU Service". I still have problems uploading the packet, as if I try to upload it I get "Error: unknown (8202)".

I guess it is not a problem with signing but with something else ?