https://devzone.nordicsemi.com/f/nordic-q-a/111117/dfu-through-ftpHi all, I am working on a project with the ncs v2.6.0 and I am trying to update the nrf5340 by downloading the new firmware update on a FTP. I am able to connect to the FTP and download the file (&quot;app_update.bin&quot; attached). When downloading I am writingen-USTelligent Community 13Mon, 13 May 2024 15:40:29 GMThttps://devzone.nordicsemi.com/thread/483111?ContentTypeID=1Mon, 13 May 2024 15:40:29 GMT137ad170-7792-4731-bb38-c0d22fbe4515:ebad693f-693c-47bc-a7a2-95aa1ed21607sguitton01<p>Hi thanks,<br />I checked my external flash memory and I saw some differeces due to the ftp being in ASCII mode instead of Binary mode.</p> <p></p> <p>Best regards,<br /><br />Sylvain</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/483014?ContentTypeID=1Mon, 13 May 2024 11:38:37 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c4847274-ab23-4ac5-858c-f40cf6e94930Vidar Berg<p>Hello,</p> <p>Is the secondary slot located in external or internal flash? Either way, I would recommend you debug the bootloader and check if it is the boot_image_check() check that fails here:&nbsp;<a href="https://github.com/nrfconnect/sdk-mcuboot/blob/3c2f2ff12bc20625cd65730b6036d061de4da5f7/boot/bootutil/src/loader.c#L819">https://github.com/nrfconnect/sdk-mcuboot/blob/3c2f2ff12bc20625cd65730b6036d061de4da5f7/boot/bootutil/src/loader.c#L819</a>&nbsp;</p> <p>You can also read out the memory content from the secondary slot and compare that to the app_update.bin to see if the image was stored correctly.</p> <p>With nrfjprog:</p> <p><pre class="ui-code" data-mode="text">$ nrfjprog --memrd &lt;secondary slot start address&gt; --n &lt;secondary slot size in bytes&gt; &gt; secondary_slot.txt</pre></p> <p>Best regards,</p> <p>Vidar</p><div style="clear:both;"></div>