DFU - Device Manager Question - Payload(250 bytes) too long for MTU: 249

[PingISTL]

Dear support

Try to perform DFU OTA on my final target board and have an error state says - "payload(250 bytes) too long for MTU: 249 "during uploading stage, could anyone let me know what is happening please? 

I have done quite a few times on a Fanstel board and had not have any problem.

Urgent help is needed please!

Ping

[tonkarhu]

I'm not sure what is your use case; are you using the play store version of the "nRF Connect Device Manager"? You can try to build the previous version from source the: https://github.com/NordicSemiconductor/Android-nRF-Connect-Device-Manager/releases. They have the sample app in the repository that you can use for testing.

In my case I have the Flutter app that imports the library "no.nordicsemi.android:mcumgr-ble:1.4.1". There might be some other ways to get it also but I'm not familiar with those.

[PingISTL]

Thanks for reply, Tonkarhu

Yes, I downloaded it from play store, I use Android phone, I don't see an option allow me to choose an old version. 

I am not sure how to build it from source code - that is a long way for me.

Any easy way to do it?

Ping

[PingISTL]

Tried to change the setting as above, still not working unfortunately - state message changes to "Payload (246 bytes) too long for MTU: 244"

I think you are right , it is a bug on new version.

Ping

[AHaug]

Yes, the two settings you mention are larger than what I suggested, so I don't think the issue is due to the MTU size since you get the same error. You could try to increase it to 512 and see if that makes any difference. 

I believe it is a max length mtu -1  issue as Tonkarthu suggests. I've reached out to the mobile team and asked about how to proceed. I'll get back to you when I know more. In the meanwhile you might try to downgrade the Device Manager App to see if that fixes the issue.

Kind regards,
Andreas

[PingISTL]

Managed to downgraded to v1.4.1 and it works now!

Thank you!

Ping