https://devzone.nordicsemi.com/f/nordic-q-a/48995/why-does-my-application-still-run-if-i-program-uicr-nrffw-0-but-leave-the-destination-blankI&#39;m debugging some corner-cases with my own DFU process and Bootloader. I believe I hit a race condition in which sd_mbr_command() was called before the source of the new Bootloader was written. Thus, the MBR copied clear flash to the Bootloader locationen-USTelligent Community 13Wed, 26 Jun 2019 09:12:57 GMThttps://devzone.nordicsemi.com/thread/194811?ContentTypeID=1Wed, 26 Jun 2019 09:12:57 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b223d89f-0e8c-4ac2-9429-3026141abadaEdvin<p>Hello,</p> <p>The MBR will always check the bootloader address to see whether there is a bootloader available. If not (if you have deleted the address) it will assume that there isn&#39;t, and it will continue to the softdevice (if there is a softdevice), which will boot up the application, or finally, boot up the application if there is no softdevice.</p><div style="clear:both;"></div>