https://devzone.nordicsemi.com/f/nordic-q-a/23568/validate-firmware-procedrueHi, I&#39;m trying to do DFU in my app, I almost complete it, I met a problem that my app flashed back when I sent 04 to the device.According to the DFU doc,after uploading firmware,and I also got 10-03-01 as response,then,I need to send 04 to validate theen-USTelligent Community 13Tue, 18 Jul 2017 12:54:00 GMThttps://devzone.nordicsemi.com/thread/92580?ContentTypeID=1Tue, 18 Jul 2017 12:54:00 GMT137ad170-7792-4731-bb38-c0d22fbe4515:8487ee0c-ae36-442b-8289-da294f771e07Hung Bui<p>It&#39;s pretty strange the app crashed that way. I assume you wrote everything from scratch and didn&#39;t use our DFU library ? Do you have any log ? or any error code thrown away ?</p><div style="clear:both;"></div>