# Dfu: unrecoverable error on read **URL:** \ **Category:** Firmware\ **Created:** [May 25, 2022, 2:43pm UTC](https://discuss.blues.com/t/dfu-unrecoverable-error-on-read/847 "2022-05-25T14:43:07Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![LBBD](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/lbbd/32/209_2.png) [@LBBD](https://discuss.blues.com/u/LBBD)\ **Post date:** [May 25, 2022, 2:43pm UTC](https://discuss.blues.com/t/dfu-unrecoverable-error-on-read/847/1 "2022-05-25T14:43:07Z")
I’ve implemented the DFU functionality, following the [Updating ESP32 Host Firmware](https://dev.blues.io/guides-and-tutorials/notecard-guides/updating-esp32-host-firmware/#updating-esp32-host-firmware) tutorial. Based on the log messages it seemed that things were progressing as expected: ```auto {"req":"dfu.get","offset":397312,"length":4096} {"payload":"hyYFMiIRhgIAN..."} dfu: successfully transferred offset:397312 len:4096 ``` Until the following error was shown in the serial monitor: ```auto {"req":"dfu.get","offset":405504,"length":4096} {"err":"not currently in the DFU operating mode (see hub.set)"} dfu: error on read: not currently in the DFU operating mode (see hub.set) dfu: reading chunk (offset:405504 length:4096 try:2) ... dfu: reading chunk (offset:405504 length:4096 try:5) {"req":"dfu.get","offset":405504,"length":4096} {"err":"not currently in the DFU operating mode (see hub.set)"} dfu: error on read: not currently in the DFU operating mode (see hub.set) dfu: unrecoverable error on read ``` Where do I go from here? I’d appreciate if someone could point me in the right direction. ---
**Author:** ![seant](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@seant](https://discuss.blues.com/u/seant)\ **Post date:** [May 25, 2022, 2:50pm UTC](https://discuss.blues.com/t/dfu-unrecoverable-error-on-read/847/2 "2022-05-25T14:50:02Z")
The Notecard DFU mode times out after 15 minutes (to prevent the risk of a Notecard left in DFU mode no longer communicating to Notehub) - is there a chance that 15 minutes had elapsed since the `{"req":"hub.set","mode":`dfu"}` ? ---
**Author:** ![LBBD](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/lbbd/32/209_2.png) [@LBBD](https://discuss.blues.com/u/LBBD)\ **Post date:** [May 25, 2022, 2:59pm UTC](https://discuss.blues.com/t/dfu-unrecoverable-error-on-read/847/3 "2022-05-25T14:59:49Z")
@seant Thanks for your quick reply. Unfortunately I didn’t monitor the entire process, so I don’t have a time record. As I saw that the update was successfully initiated I turned away from the monitor and when I came back later I noticed the error. ---
**Author:** ![LBBD](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/lbbd/32/209_2.png) [@LBBD](https://discuss.blues.com/u/LBBD)\ **Post date:** [May 25, 2022, 3:09pm UTC](https://discuss.blues.com/t/dfu-unrecoverable-error-on-read/847/4 "2022-05-25T15:09:39Z")
@seant I see that the data transfer started again and this time I was able to roughly time the beginning. I’ll see how and when the process ends and I’ll get back to you with the results. ---
**Author:** ![LBBD](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/lbbd/32/209_2.png) [@LBBD](https://discuss.blues.com/u/LBBD)\ **Post date:** [May 25, 2022, 3:22pm UTC](https://discuss.blues.com/t/dfu-unrecoverable-error-on-read/847/5 "2022-05-25T15:22:51Z")
@seant The same error occurred and indeed it seems that it happened around the 15 minute mark. The size of the firmware .bin file is 499KB. ---
**Author:** ![seant](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@seant](https://discuss.blues.com/u/seant)\ **Post date:** [May 25, 2022, 4:53pm UTC](https://discuss.blues.com/t/dfu-unrecoverable-error-on-read/847/6 "2022-05-25T16:53:43Z")
@LBBD If the binary transfer is taking more than 15 minutes to complete you may be able to restart the 15 minute timeout by issuing further `{"req":"hub.set","mode":dfu"}` requests periodically during the repeated `{"req":"dfu.get"}` requests. We are aware of the possibility of timeout of long transfers and in future Notecard firmware we restart the 15 minute timer on each `dfu.get` request. ---
**Author:** ![LBBD](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.blues.com/lbbd/32/209_2.png) [@LBBD](https://discuss.blues.com/u/LBBD)\ **Post date:** [May 25, 2022, 6:15pm UTC](https://discuss.blues.com/t/dfu-unrecoverable-error-on-read/847/7 "2022-05-25T18:15:36Z")
@seant , thanks for the suggestion. The repeated `{"req":"hub.set","mode":dfu"}` solved the timeout issue and the update was completed successfully.