https://devzone.nordicsemi.com/f/nordic-q-a/23952/uart-bootloader---migrating-from-sd11-to-sdk13Hello, I&#39;ve been using UART DFU feature quite extensively in one project which caused that I had to stick to SDK11 features (since bootloader relied on SD 132 2.0.0). Recently, in SDK13 the UART DFU came back and after having experimenting withen-USTelligent Community 13Tue, 01 Aug 2017 14:23:20 GMThttps://devzone.nordicsemi.com/thread/94298?ContentTypeID=1Tue, 01 Aug 2017 14:23:20 GMT137ad170-7792-4731-bb38-c0d22fbe4515:d75ab262-5e64-4c3d-acea-36400354305dbjorn-spockeli<p>Hi PB,</p> <p>the Secure Serial Bootloader is larger than the Legacy Serial Bootloader from SDK v11.0.0. If you&#39;re trying to update to the Secure Serial Bootloader then you&#39;re probably getting the <code>REMOTE DFU DATA SIZE EXCEEDS LIMIT</code></p> <p>This is because the new bootloader image must have the same start address as the old image, i.e. the new image cannot be larger than the old bootloader and if its smaller it must still have the same start address. This is because the bootloader start address is written to a UICR register, which the MBR jumps to during startup.</p> <p>It is possible to workaround this using the approach described in <a href="https://devzone.nordicsemi.com/question/105922/dfu-updating-from-legacysdk-v1100-bootloader-to-securesdk-v12x0-bootloader/">this</a> answer.</p> <p>Best regards</p> <p>Bjørn</p><div style="clear:both;"></div>