https://devzone.nordicsemi.com/f/nordic-q-a/82663/unable-to-enter-legacy-dfu-modeHi, It&#39;s been a few months since I&#39;ve been developing a new project using the nrf52832. One of the main features is naturally the OTA DFU. During the last months I was able to successfully update the firmware using the nrf connect and nrf toolbox appsen-USTelligent Community 13Wed, 15 Dec 2021 09:52:07 GMThttps://devzone.nordicsemi.com/thread/343577?ContentTypeID=1Wed, 15 Dec 2021 09:52:07 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f240047b-b05f-47b2-afb8-72293d7529ecSigurd<p>Hi,</p> [quote user=""]When I start the DFU process, the device correctly writes the 0x0104 value to the DFU Control characteristic and then reboots. At that point I would expect the system to boot in the DFU mode from the bootloader, but interestingly enough boots again from my APP image.[/quote] <p>Could you debug your app,&nbsp;set&nbsp;a breakpoint in&nbsp;<span>dfu_app_handler.c::bootloader_start(), and see if it&#39;s called?</span></p> <p><span>If is not called, then there could have been an assert/error that triggered a reset before&nbsp;dfu_app_handler.c::bootloader_start() was called.</span></p><div style="clear:both;"></div>