# Bootloader for OTA Updates **URL:** \ **Category:** Firmware\ **Created:** [March 10, 2026, 3:40pm UTC](https://discuss.blues.com/t/bootloader-for-ota-updates/3491 "2026-03-10T15:40:19Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![jbro](https://avatars.discourse-cdn.com/v4/letter/j/fbc32d/32.png) [@jbro](https://discuss.blues.com/u/jbro)\ **Post date:** [March 10, 2026, 3:40pm UTC](https://discuss.blues.com/t/bootloader-for-ota-updates/3491/1 "2026-03-10T15:40:19Z")
I’m using the Adafruit Feather nRF52840 Express (Product ID 4062) with the Arduino IDE (Adafruit nRF52 core) and trying to implement over-the-air firmware updates using a Blues Notecard and Notehub. When I export compiled binaries from Arduino I receive `.hex` and `.elf` files, which I then convert to `.bin` and package using the Blues `binpack` tool as required for the Notehub OTA workflow. However, when attempting the update, the DFU update fails on the device. My question is about bootloader compatibility: Does the default UF2 bootloader on the Feather nRF52840 Express support firmware updates delivered through an external OTA system like Blues Notehub, or would this require a different bootloader or a custom firmware update implementation in the application? Just trying to confirm whether the standard Feather bootloader supports this type of OTA pipeline, or if my approach is incompatible with the default bootloader. Thank you! ---
**Author:** ![RobLauer](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/roblauer/32/1567_2.png) [@RobLauer](https://discuss.blues.com/u/RobLauer)\ **Post date:** [March 10, 2026, 11:25pm UTC](https://discuss.blues.com/t/bootloader-for-ota-updates/3491/3 "2026-03-10T23:25:58Z")
Hi @jbro and welcome to the Blues community! Did you by any chance see this thread? At first glance it may help unblock you: > [@Difficulty with mcuboot and nRF52840, can't leave bootloader mode](https://discuss.blues.com/t/difficulty-with-mcuboot-and-nrf52840-cant-leave-bootloader-mode/2179): > > Hi all, I’m using the Legacy Notecard Cellular on a Notecarrier-F, with an Adafruit nRF52840 Feather Express, developing with Nordic’s nRF Connect SDK in Visual Studio Code. I’m trying to get outboard DFU working, and am running into a problem where the board just goes into DFU mode all the time and will never run app code. Figuring I must be overlooking something, I decided to just try to get this example project working, straight out of git: I’m seeing the same symptom with this example a… If not, just let me know. Thanks, Rob ---
**Author:** ![scase](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@scase](https://discuss.blues.com/u/scase)\ **Post date:** [March 11, 2026, 2:40pm UTC](https://discuss.blues.com/t/bootloader-for-ota-updates/3491/4 "2026-03-11T14:40:24Z")
This page seems to be talking about using the UF2 bootloader, so it seems safe to say your approach could work: > **[note-outboard-dfu/nrf52840 at main · blues/note-outboard-dfu](https://github.com/blues/note-outboard-dfu/tree/main/nrf52840)** > > Resources for testing and demonstrating Notecard Outboard Firmware Update - blues/note-outboard-dfu Also this page, linked from there, had some potentially helpful info on it, but now it’s 404. Maybe Blues can resurrect it? [https://github.com/blues/note-outboard-dfu/blob/main/nrf52840/blinky/Arduino](https://github.com/blues/note-outboard-dfu/blob/main/nrf52840/blinky/Arduino) ---
**Author:** ![devElert](https://avatars.discourse-cdn.com/v4/letter/d/8e8cbc/32.png) [@devElert](https://discuss.blues.com/u/devElert)\ **Post date:** [March 11, 2026, 7:17pm UTC](https://discuss.blues.com/t/bootloader-for-ota-updates/3491/5 "2026-03-11T19:17:13Z")
I think that 404 page is now here - [note-outboard-dfu/nrf52840/blinky/arduino at main · blues/note-outboard-dfu · GitHub](https://github.com/blues/note-outboard-dfu/tree/main/nrf52840/blinky/arduino)