I can DFU with segger but directly downloading secure bootloader hex file onto nRF52840 won&#39;t let me dfu?https://devzone.nordicsemi.com/f/nordic-q-a/56515/i-can-dfu-with-segger-but-directly-downloading-secure-bootloader-hex-file-onto-nrf52840-won-t-let-me-dfuHi devzone, I learnt DFU through USB by performing the following steps: 1. build and run &quot;secure bootloader usb&quot; project with segger through J-link port J2. 2. flash a signed zip package using nrfutil through usb port J3. And it was successfulen-USTelligent Community 13Tue, 14 Jan 2020 14:51:03 GMTRE: I can DFU with segger but directly downloading secure bootloader hex file onto nRF52840 won't let me dfu?https://devzone.nordicsemi.com/thread/229092?ContentTypeID=1Tue, 14 Jan 2020 14:51:03 GMT137ad170-7792-4731-bb38-c0d22fbe4515:10caa001-8943-4d12-ab55-9f4aa88db337Hung Bui<p>Hi,<br /><br /></p> <p>Please be aware that the example is created to work with an MBR flashed into the chip. Without the MBR the bootloader won&#39;t work. The MBR is included when you flash using Segger Embedded Studio. You can find the additional file in Project Options -&gt; Loader -&gt; Additional Load File.</p> <p>If you want to flash using Jlink Commander or using nrfjprog, you would need to flash the mbr (either before or after) with the bootloader hex file.&nbsp;</p><div style="clear:both;"></div>