https://devzone.nordicsemi.com/f/nordic-q-a/36989/questions-about-upgrade-bootloader-otaHi support team, I&#39;m using a PDK(PCA10056) with nrf52840 and SDK 15.0. Recently I was developing a BLE bootloader for DFU OTA. Since the ble bootloader was depended on softdevice, if I want to update softdevice to another major version which willen-USTelligent Community 13Wed, 15 Aug 2018 08:01:10 GMThttps://devzone.nordicsemi.com/thread/144266?ContentTypeID=1Wed, 15 Aug 2018 08:01:10 GMT137ad170-7792-4731-bb38-c0d22fbe4515:fa0cef65-f123-4466-9c10-849bcdef1503Susheel Nuguru<p>Hi,</p> <p>Apologies for the late reply, something this thread missed our sight.</p> <p>1) MBR is part of softdevice release, yes. You do not need to update MBR if you update the softdevice.</p> <p>2)&nbsp;The device is not bricked. MBR/bootloader are able to detect and abrupt power loss during DFU and are able to recover from that situation. Look into the thread <a href="https://devzone.nordicsemi.com/f/nordic-q-a/27474/reset-dfu-process-after-power-loss">here</a></p> <p>3) The statemachine and process is explained <a href="http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v15.0.0%2Flib_bootloader_dfu_process.html&amp;cp=4_0_0_3_5_1">here</a></p> <p>Your understanding is correct about MBR/Bootloader responsibilities.</p><div style="clear:both;"></div>