https://devzone.nordicsemi.com/f/nordic-q-a/74179/spi-dfu-bootloader-protocolHi, I am currently working on SDK 15.2.0 on my NRF52840 DK to program a bootloader that can do DFUs over SPI. I have been following the protocol found in this link . I have been able to get a DFU_Master to talk to the Slave_bootloader, however, whenen-USTelligent Community 13Tue, 20 Apr 2021 14:10:36 GMThttps://devzone.nordicsemi.com/thread/305898?ContentTypeID=1Tue, 20 Apr 2021 14:10:36 GMT137ad170-7792-4731-bb38-c0d22fbe4515:09ec94d7-66e8-45c7-86d7-3c16b6294896Edvin<p>Hello,</p> <p>Since we don&#39;t support SPI bootloaders, I assume you have done some of this implementation yourself. You say that the error says:&nbsp;<span>execute with faulty offset. What offset do you send from the SPI command, and what does it expect? Try setting a breakpoint in&nbsp;nrf_dfu_validation_init_cmd_execute() and check what the&nbsp;s_dfu_settings.progress.command_offset and&nbsp;s_dfu_settings.progress.command_size is.</span></p> <p><span></span></p> <p><span>Best regards,</span></p> <p><span>Edvin</span></p><div style="clear:both;"></div>