https://devzone.nordicsemi.com/f/nordic-q-a/78896/the-dfu-upgrade-of-nrf52840-failed-procedureWhy is it so easy to disconnect when upgrading to a few points? The upgrade may be complete I used SDK 17.0.2&#39;s ble_APP_ButtonLess_dFU routine Do you know? Thank you for guiding me!en-USTelligent Community 13Tue, 24 Aug 2021 11:01:16 GMThttps://devzone.nordicsemi.com/thread/326334?ContentTypeID=1Tue, 24 Aug 2021 11:01:16 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c3782320-5a2e-43a6-a042-64b005749dafAmanda Hsieh<p>Hi,&nbsp;</p> <p>Do you update with&nbsp;<span>SD (+ BL) + APP in one package?</span></p> <p><span>See&nbsp;</span><a title="https://infocenter.nordicsemi.com/topic/ug_nrfutil/ug/nrfutil/dfu_package_combinations.html?resultof=%22%2d%2d%73%64%2d%69%64%22%20" href="https://infocenter.nordicsemi.com/topic/ug_nrfutil/UG/nrfutil/dfu_package_combinations.html?resultof=%22%2d%2d%73%64%2d%69%64%22%20" rel="noopener noreferrer" target="_blank">DFU package combinations</a>:</p> <p><em>The SD (+ BL) + APP update is done with two consecutive connections unless a custom bootloader is used. First the SD (+ BL) is updated, then the bootloader will disconnect and the (new) BL will start advertising. Then the second connection to the bootloader will update the APP.</em></p> <p><span>-Amanda H.</span></p><div style="clear:both;"></div>