https://devzone.nordicsemi.com/f/nordic-q-a/117620/serial-bootloader-unable-to-boot-app-with-softdeviceHello everyone. I work with nrf52840 chip and previously I had an app with softdevice (s140) and use BLE bootloader. Everything works as expected. Next I want to use another bootloader, serial. I took an example from SDK17.1.0, setup for my purposes,en-USTelligent Community 13Mon, 30 Dec 2024 14:56:55 GMThttps://devzone.nordicsemi.com/thread/516527?ContentTypeID=1Mon, 30 Dec 2024 14:56:55 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c595d49d-da91-491f-a69b-ce7b31c968dbHung Bui<p>Hi Alex,&nbsp;<br />There are 2 things you may want to look into.</p> <p>1. Make sure you erase flash completely when you try to test with the bootloader. There could be data in UICR that has not be erased before you test.&nbsp;</p> <p>2. Check the application data to see if it may put data into the area where bootloader may erase.&nbsp;<br /><br />What you can try to test is to test the same bootloader with a blinky example. Try the blinky with mbr (no softdevice)</p> <p>After that try to test with a simple BLE example to see if it works.&nbsp;</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/516427?ContentTypeID=1Sun, 29 Dec 2024 04:42:19 GMT137ad170-7792-4731-bb38-c0d22fbe4515:13a64536-f5b8-4931-b5b5-cc05529816a8AlexVrubel<p>After a lot of rebuilds, changing flash placements and try different build configurations, finnaly bootloader starts app without any changes in code or flashplacement. What is this a bug?</p> <p><img style="max-height:240px;max-width:320px;" src="https://devzone.nordicsemi.com/resized-image/__size/640x480/__key/communityserver-discussions-components-files/4/_21043D0438043C043E043A04_-_4D043A04400430043D043004_-2024_2D00_12_2D00_29-_3204_-06.40.34.png" alt=" " /></p><div style="clear:both;"></div>