https://devzone.nordicsemi.com/f/nordic-q-a/57877/stuck-in-bootloader-during-dfuHi, I was testing the various cases for DFU &amp; I was looking for any possible solutions to fix the issue. I flashed SD + bootloader (secure) + app from SDK 15.2 on the BLE chip. I was able to replace the app firmware file (from SDK 15.2) using nrfconnecten-USTelligent Community 13Mon, 17 Feb 2020 13:50:54 GMThttps://devzone.nordicsemi.com/thread/234665?ContentTypeID=1Mon, 17 Feb 2020 13:50:54 GMT137ad170-7792-4731-bb38-c0d22fbe4515:ef9a70ba-2975-4382-a849-d1811a9cd4ecHung Bui<p>Hi Sonal,&nbsp;</p> <p>Could you provide the rejection reason on nRF Connect when you try to update the app separately. Please check the log on both the bootloader and the nRF Connect app.&nbsp;</p> <p><br />Could you try using only&nbsp;<span>--application-version 2&nbsp; and no&nbsp;--application-version-string.&nbsp;</span></p> <p><span>Also please try to test with --application-version 3</span></p><div style="clear:both;"></div>