https://devzone.nordicsemi.com/f/nordic-q-a/75441/data-loss-after-dfu-updateThe serial number of the product is stored in the memory of the nRF52. After DFU update, this memory area is erased (or changed to new one from new FW). Please let us know how we can save data on chip&#39;s memory in a proper way (and not loss in while DFUen-USTelligent Community 13Fri, 21 May 2021 13:27:41 GMThttps://devzone.nordicsemi.com/thread/311075?ContentTypeID=1Fri, 21 May 2021 13:27:41 GMT137ad170-7792-4731-bb38-c0d22fbe4515:056d091b-5122-4fd8-81a3-b613a6569177YaroslavRakhnenko<p>Thank you!</p> <p>solution (based on your reply):</p> <p><br />DFU_APP_DATA_RESERVED = CODE_PAGE_SIZE * 8&nbsp; (see nrf_dfu_utils for datails)<br />A flash page is 1024 32-bit words which is 4096 byte. <br />8 flash pages are 32k =&gt; 0x8000. The start address is END_ADDRESS - 0x8000<br />END_ADDRESS = BOOTLOADER_START_ADDR = 0x78000 =&gt; 0x78000-0x8000=0x6E000<br />DFU_APP_DATA_ADDR =&nbsp; 0x6E000</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/310964?ContentTypeID=1Fri, 21 May 2021 09:13:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:d78990a3-e3e9-42f3-8bc4-0c54960c9451William.wei<p>there is setting in&nbsp;bootloader :<code>DFU_APP_DATA_RESERVED</code><br /><br />please see this post:<a href="https://devzone.nordicsemi.com/f/nordic-q-a/17185/updating-the-dfu-with-different-app-data-reserve-size">https://devzone.nordicsemi.com/f/nordic-q-a/17185/updating-the-dfu-with-different-app-data-reserve-size</a></p><div style="clear:both;"></div>