https://devzone.nordicsemi.com/f/nordic-q-a/16280/handling-ble_error_gatts_sys_attr_missingI am doing some test with the Battery Service on SDK v10, and found out that if I have not enabled Notification on my phone, calling ble_bas_battery_level_update() returns BLE_ERROR_GATTS_SYS_ATTR_MISSING , which originated from a call to sd_ble_gatts_hvxen-USTelligent Community 13Mon, 12 Sep 2016 12:23:42 GMThttps://devzone.nordicsemi.com/thread/62226?ContentTypeID=1Mon, 12 Sep 2016 12:23:42 GMT137ad170-7792-4731-bb38-c0d22fbe4515:9708e621-35c4-4026-b4bf-dc51085e648ePetter Myhre<ol> <li>_</li> <li>If the CCCD is actually set to 0x0000, you will not receive BLE_ERROR_GATTS_SYS_ATTR_MISSING, you will receive NRF_ERROR_INVALID_STATE.</li> <li>As far as I know, you will only receive BLE_GATTS_EVT_SYS_ATTR_MISSING if the peer tries to read a CCCD that hasn&#39;t been set.</li> </ol><div style="clear:both;"></div>