https://devzone.nordicsemi.com/f/nordic-q-a/29462/using-sdk-13-0-0-serial-secure-dfu-bootloader-with-sd-3-0-0Hi I am currently using SDK 12.1.0 with SD 3.0.0. I want to add the option for serial DFU, which was added in SDK 13.0.0. I wonder if I can implement the serial bootloader like in SDK 13 without upgrading my SD version. Thanks Yaronen-USTelligent Community 13Tue, 16 Jan 2018 10:06:02 GMThttps://devzone.nordicsemi.com/thread/117148?ContentTypeID=1Tue, 16 Jan 2018 10:06:02 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5eccded2-694c-4c4f-a168-3e668046a103Hung Bui<p>Hi Yaron,</p> <p>The APIs are not exactly the same, you would need to modify the bootloader to use the older Softdevice. But I don&#39;t think it would be very difficult to do so. Note that if you plan to do DFU softdevice update, we strongly suggest you to use the latest bootloader there was some bugs with the bootloader in <a href="https://devzone.nordicsemi.com/question/169172/update-sdblapp-from-sdk-v13-to-v14-via-dfu-fails/">SDK v13 and 14.0</a></p> <p>Updating application should be fine.</p><div style="clear:both;"></div>