https://devzone.nordicsemi.com/f/nordic-q-a/69530/sd_ble_gap_addr_set-is-the-correct-way-to-change-device-real-macHi, I try to change my MAC address, but return error code 8. check error code 8 is : So I try set the mac address after ble connected. and the function sd_ble_gap_addr_set retrun success, and try use sd_ble_gap_addr_get is what my last seten-USTelligent Community 13Tue, 15 Dec 2020 12:25:40 GMThttps://devzone.nordicsemi.com/thread/285054?ContentTypeID=1Tue, 15 Dec 2020 12:25:40 GMT137ad170-7792-4731-bb38-c0d22fbe4515:3e7a1c0f-27b8-491f-a4f6-040c6c4deba9Vidar Berg<p><span><span>Hi,</span></span></p> <p><span><span>The address must be set with </span><a title="sd_ble_gap_addr_set" href="https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s132.api.v7.2.0/group___b_l_e___g_a_p___f_u_n_c_t_i_o_n_s.html?cp=4_7_3_1_2_1_3_1#gaef69dc212534adf4b78d211edce2267b">sd_ble_gap_addr_set() </a></span><span>before you start start advertising or enter a connection, otherwise it will return error 8 (NRF_ERROR_INVALID_STATE) as you experienced.</span></p> [quote user=""]But after device reboot ,&nbsp; MAC change back to the origin Nordic random MAC address!!![/quote] <p>&nbsp;This is as excepted. The Softdevice will not store the address you provide in persistent memory, so you have to call sd_ble_gap_addr_set() with your address on every reboot (unless you want to use the device&#39;s random address)</p> <p>Best regards,</p> <p>Vidar</p><div style="clear:both;"></div>