https://devzone.nordicsemi.com/f/nordic-q-a/70879/ota-dfu-bootloader-updating-issueHi All I’m making a few tests on a custom board equipped with a nRF51822-AA device trying to update the firmware with a newest one based on a more recent SDK The original code is based on the old SDK 7.1.0 / 7.2.0 release Bootloader: nRF51_SDK_7en-USTelligent Community 13Thu, 28 Jan 2021 14:37:16 GMThttps://devzone.nordicsemi.com/thread/291828?ContentTypeID=1Thu, 28 Jan 2021 14:37:16 GMT137ad170-7792-4731-bb38-c0d22fbe4515:1a8c1440-e0a7-4078-8b3d-37fbbb2990f1Vidar Berg<p>Hello Cristian,</p> <p>Bootloader updates should be supported in this release. Are you able to debug the bootloader to see if maybe the update is aborted because the post validation step is failing (dfu_init_postvalidate)? I am thinking it might be a mistmatch between the CRC value in the init packet and the calculated CRC of the received bootloader image.</p> <p>Best regards,</p> <p>Vidar</p><div style="clear:both;"></div>