https://devzone.nordicsemi.com/f/nordic-q-a/26612/potential-fds-bugHi, I just found, fds initialization sequence is important for fds_event_handler to be called. My scenario: nrf52832 SDK 12.2.0 MDK My sequence to call fds initialisation is as follows: User fds_register user fds_initen-USTelligent Community 13Sun, 12 Nov 2017 14:02:51 GMThttps://devzone.nordicsemi.com/thread/104691?ContentTypeID=1Sun, 12 Nov 2017 14:02:51 GMT137ad170-7792-4731-bb38-c0d22fbe4515:0a2a5a1e-b9ef-44a8-a48c-3b0e9e521adfnine-fox<p>Hi emdi,</p> <p>Thanks a lot for your confirmation. You are right, after I install fds after softdevice enabled, everything works fine.</p> <p>Base on that, I am happy to close it.</p> <p>Vincent</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/104690?ContentTypeID=1Mon, 06 Nov 2017 13:57:11 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e4f056cd-8d13-42d9-b14b-9f712df4707bemdi<p>Hi,</p> <p>fds in SDK 12.2 can&#39;t write to flash if the SoftDevice is disabled.</p> <p>If fds is not &#39;installed&#39; it needs the SoftDevice to be enabled to install upon booting the first time. After that first boot, it is possible to initialize fds and read even if the SoftDevice is disabled, but still you won&#39;t be able to write.</p> <p>It might be possible that you don&#39;t <em>need</em> to start advertising right after you enable the stack: you could enable the stack, do all the flash operations you need to (read/write) and determine whether to start advertising or scanning or whatnot at a later point. Enabling the stack and advertising/scanning are different things.</p> <p>Regards, emdi</p><div style="clear:both;"></div>