Both on android and IOS stops DFU process if device reports busy using Nordic DFU_MCUMGR lib

RE: Both on android and IOS stops DFU process if device reports busy using Nordic DFU_MCUMGR lib

Dinesh Harjani — Wed, 25 Mar 2026 11:22:18 GMT

Bit of follow-up - there's a possible fix in the main branch. Let me know when you've tested it.

RE: Both on android and IOS stops DFU process if device reports busy using Nordic DFU_MCUMGR lib

Dinesh Harjani — Tue, 24 Mar 2026 10:09:57 GMT

Hi Tommy. Dinesh here, I maintain the iOS DFU Library (McuMgr).

Are you guys able to pull from main branch and test a possible fix for this? Or do you need a release? This is so I can push a possible fix, so you guys can test whether it works for you or not, and provide some feedback without the need for a release without knowing for sure if it works out.

Thanks.

RE: Both on android and IOS stops DFU process if device reports busy using Nordic DFU_MCUMGR lib

Aleksander Nowakowski — Mon, 23 Mar 2026 12:47:21 GMT

Hi, yes, we will handle this status in the library. We will soon switch to nRF Connect Device Manager project.

RE: Both on android and IOS stops DFU process if device reports busy using Nordic DFU_MCUMGR lib

Tommy F Kristensen — Fri, 20 Mar 2026 07:26:32 GMT

Hi Alexander

Are you planning to make some error handling inside the library. We have handled in our app firmware on both platforms(IOS/Android) in the callback onUpgradeFailed, where we have added a retry logic.

But I think that a busy should not lead to onUpgradeFailed on first error.

Best Regards

Tommy F Kristensen

RE: Both on android and IOS stops DFU process if device reports busy using Nordic DFU_MCUMGR lib

Tommy F Kristensen — Tue, 10 Mar 2026 07:23:41 GMT

Hi Alexander

Thanks for your answer

we are using the external flash for both DFU and external filesystem and occasinally it can be BUSY, so thats why we need handle it :-)

Best Regards

Tommy F Kristensen

RE: Both on android and IOS stops DFU process if device reports busy using Nordic DFU_MCUMGR lib

Aleksander Nowakowski — Mon, 09 Mar 2026 12:36:08 GMT

Thank you for the detailed explanation. We will look into this.

We are not that busy, so we actually never got that error from the device ;)

RE: Both on android and IOS stops DFU process if device reports busy using Nordic DFU_MCUMGR lib

Tommy F Kristensen — Fri, 06 Mar 2026 09:20:06 GMT

Hi Vidar

Thanks for your answer

I have been strugling a lot this to understand what did happend.

By default the FirmwareUpgradeController, does not handle errorcodes like 0x10 (BUSY) from target, it calls onUpgradeFailed. We did implement a retry if the device did report BUSY. This works ok the first 10 times, then the error 257 comes(This error is not coming from the target, but from the Android system(insufficient resources)).

override fun onUpgradeFailed(state: FirmwareUpgradeManager.State?, error: McuMgrException?) {
    logger.error(TAG, "(BT) DFU failed: $state, error: $error")
    firmwareUpgradeController = null     if (error != null &&
       error.code.value() == 10 &&
(state == FirmwareUpgradeManager.State.VALIDATE || state == FirmwareUpgradeManager.State.UPLOAD) &&
retryAttempt < MAX_BUSY_RETRIES ) {
scheduleBusyRetry()
return }

In scheduleBusyRetry() we basically reastarted a new dfu, and it resumes the DFU process perfectly 10 times,
but the issue was that the transport was not reused doing a restart of the the DFU process and a new instance was created each time.

transport = McuMgrBleTransport(context, bluetoothDevice.bluetoothDevice)

val dfuManager = FirmwareUpgradeManager(transport, dfuCallback)
...
It started working after we did start to reuse the transport,
but it was quite hard to figure out cause the only error code we got was error 257,
Fix:
Done Once on dfustart
lastDevice = bluetoothDevice.bluetoothDevice
lasttransport = McuMgrBleTransport(context, lastDevice!!)
...
Done on each retry
val dfuManager = FirmwareUpgradeManager(lasttransport , dfuCallback)
....
It would be nice if the library had implemented some error handling retry on Busy and Timeout from the taget,
not ending in a callback upgradefailed.
This error is seen on both Android and IOS

Best Regards
Tommy F Kristensen

RE: Both on android and IOS stops DFU process if device reports busy using Nordic DFU_MCUMGR lib

Vidar Berg — Wed, 04 Mar 2026 14:25:30 GMT

Hi Tommy,

I have reached out to our app developers to see if they have any suggestions to this. Will let you know as soon as I have heard back from them.

Best regards,

Vidar