https://devzone.nordicsemi.com/f/nordic-q-a/42575/52832-upgrade-bootloader-via-nrf-connect-app-nfudear in the case :our product is produced in factory, we want to upgrade new app via phone, but the crc of new app is not equal with the origin one which store in the bootsetting. so,it is a tough problem. we want to at first change boot loaderen-USTelligent Community 13Wed, 16 Jan 2019 13:52:31 GMThttps://devzone.nordicsemi.com/thread/166000?ContentTypeID=1Wed, 16 Jan 2019 13:52:31 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6d4378f3-1fda-4fe8-af42-f585e315334btesc<p>Hi,</p> <p>I think there are some misunderstandings here.</p> <p>If you use over-the-air DFU update, you can do that either with phone app or with PC tools such as nRF Connect for Desktop or nrfutil.</p> <p>The only thing you would need bootloader settings page for, is if you program the app directly. In that case, the bootloader settings page must be generated especially for the app.</p> <p>If you update the application using DFU, the bootloader will replace the CRC as part of the DFU process.</p> <p>So:<br />1) Is it still an option to download the firmware using a programmer?</p> <p>If yes, you should generate a new bootloader settings page, erase the flash pages for bootloader settings page and application, and download the new bootloader settings page and application, all of this using a programmer.</p> <p>2) Alternatively you can use smartphone or PC to perform DFU in order to upload the new application.</p> <p>Regards,<br />Terje</p><div style="clear:both;"></div>