https://devzone.nordicsemi.com/f/nordic-q-a/35919/auto-reconnection-fails-after-disconnecthello there! I am working on a project in which two devices(one is central and other is peripheral ) uses Nordic bluetooth controller nRF51822 for connection and data exchange. Currently the peripheral device that will connect and pair with one centralen-USTelligent Community 13Fri, 29 Jun 2018 09:42:55 GMThttps://devzone.nordicsemi.com/thread/138243?ContentTypeID=1Fri, 29 Jun 2018 09:42:55 GMT137ad170-7792-4731-bb38-c0d22fbe4515:8bc7d209-2dd8-45db-a649-ce340fa492b2Bastien Reynard<p>Hi,&nbsp;</p> <p>Check this&nbsp;<a href="https://devzone.nordicsemi.com/f/nordic-q-a/3561/how-to-handle-nrf_error_invalid_state-of-sd_ble_gap_scan_start/12901#12901">answer</a>, it might be useful.</p> <p>Most probably - when calling sd_ble_gap_scan_start - your central device is busy connecting to a peripheral or a flash operation is ongoing, in which case you&#39;ll have to check the flash operations events&nbsp;in the system event handler.</p><div style="clear:both;"></div>