https://devzone.nordicsemi.com/f/nordic-q-a/43398/application-update-with-different-bootloaderHi , Does the Application update depend on bootloader version? . I changed the boot loader but application remains same on my device , hence the device is not booting up. So what is the relation between bootloader and application? how i can build newen-USTelligent Community 13Wed, 06 Feb 2019 12:08:52 GMThttps://devzone.nordicsemi.com/thread/169703?ContentTypeID=1Wed, 06 Feb 2019 12:08:52 GMT137ad170-7792-4731-bb38-c0d22fbe4515:289d25ae-ad31-4289-977c-2fbf76fe4898Vidar Berg<p>Hi,</p> <p>The last page in flash should contain information about the application that is needed by the&nbsp;bootloader to validate and boot the app (checksum + app valid flag). The bootloader should enter DFU mode if it fails to validate the app.&nbsp; Maybe you erased this page when you programmed the new bootloader? Also, what is the difference between the old and new bootloader, are they based on the same SDK?&nbsp;</p> <p>Note that you can generate a valid settings page for your application with <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.tools/dita/tools/nrfutil/nrfutil_settings_generate_display.html?cp=5_5_6">nrfutil</a>&nbsp;(assuming you are using SDK 12.x.x or newer).&nbsp;</p><div style="clear:both;"></div>