https://devzone.nordicsemi.com/f/nordic-q-a/3580/can-not-stop-advertising-in-ble-event-handlerI tried code like static void on_ble_evt(ble_evt_t * p_ble_evt) { .... case BLE_GAP_EVT_TIMEOUT: if (p_ble_evt-&gt;evt.gap_evt.params.timeout.src == BLE_GAP_TIMEOUT_SRC_ADVERTISEMENT) { err_code = sd_ble_gap_adv_stop(); // Stop advertisingen-USTelligent Community 13Sat, 23 Aug 2014 08:12:47 GMThttps://devzone.nordicsemi.com/thread/12977?ContentTypeID=1Sat, 23 Aug 2014 08:12:47 GMT137ad170-7792-4731-bb38-c0d22fbe4515:521ca022-4323-4fe9-9d07-7ffbe98b3295Nikita<p>When you configure advertising timeout with adv_params.timeout when you start advertising with sd_ble_gap_adv_start(&amp;adv_params) it means that after this interval of time if no one connect to your device then it&#39;ll stop advertising automatically.</p> <p>When you meet condition (p_ble_evt-&gt;evt.gap_evt.params.timeout.src == BLE_GAP_TIMEOUT_SRC_ADVERTISEMENT) it meens that advertising has timed out and stopped. So you get NRF_ERROR_INVALID_STATE because advertising already stopped when you call sd_ble_gap_adv_stop().</p><div style="clear:both;"></div>