https://devzone.nordicsemi.com/f/nordic-q-a/46464/why-the-app-keeping-resetHi, the bootloader addr is start form 0x28000, and I checked my application code, it only reached 0x25B00. I called the fstroge to erased a page Flash start from 0x27000. then I writed 4 bytes into flash address 0x27000. everything goes fine ecepteen-USTelligent Community 13Tue, 23 Apr 2019 13:25:19 GMThttps://devzone.nordicsemi.com/thread/183137?ContentTypeID=1Tue, 23 Apr 2019 13:25:19 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e3565867-31c6-48e7-b83d-20eaf7c83b36Einar Thorsrud<p>Hi,</p> <p>FDS_ERR_NO_PAGES is returned if there are no data pages or no swap page, and the page is not fully erased (see implementation of&nbsp;pages_init()). Therefor it seems <em>something</em> has corrupted the FDS pages. Do you do any writes to flash without using FDS, and could it be that you accidentally wrote to the pages used by FDS? Or is it the application that overlaps with the FDS pages? How many pages have you set aside for FDS? (Since your application ends at 0x25B00 and the bootloader starts at 0x28000 this means that you only have room for two pages - one swap and one data).</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/182964?ContentTypeID=1Tue, 23 Apr 2019 02:32:45 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f976db8b-7ac0-4d8f-ad90-1989855c9cc6BRN<p>I debuged, the reset rease is &quot; fds_init() returned 0x0B&quot; 0x0B shoud be&nbsp;FDS_ERR_NO_PAGES.</p> <p>If I don&#39;t write the FLASH, the system runs well, when I werite data into FLASH, then reset, the system cannot work.</p><div style="clear:both;"></div>