Getting "Sending unknown message (50) " continously on 4.3.0 custom build

[Ltomi78]

IF YOU DON'T REMOVE THESE FOUR LINES, THEN YOUR REPORT WILL BE CLOSED AUTOMATICALLY
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Bug report

Issue details
I ve got information from Randy Mackay the reason is there is a coding error in this line in custom fw.
https://github.com/ArduPilot/ardupilot/blob/master/libraries/GCS_MAVLink/GCS_Common.cpp#L5752
Please describe the problem
I upload 4.3.0 custom build fw https://custom.ardupilot.org/ and now getting this message continously:
"Sending Unknown message (50)"
Setup is: Fc matek f405 wing + gps and compass
Version
4.3.0 build with custom fw builder for matek f405 wing target

Platform
[ ] All
[ ] AntennaTracker
[ ] Copter
[X ] Plane
[ ] Rover
[ ] Submarine

Airframe type
flying wing

Hardware type
_What autopilot hardware was used?
Matek F405 wing

Logs
Please provide a link to any relevant logs that show the issue

https://github.com/ArduPilot/ardupilot/blob/master/libraries/GCS_MAVLink/GCS_Common.cpp#L5752

[macfly1202]

I have this error on MATEK F405 target too, with custom firmware ArduPlane V4.3.0dev (f9bc7e4).
Displayed on DJI FPV OSD.

[IamPete1]

Fixed by #21828

[Ltomi78]

I have this error on MATEK F405 target too, with custom firmware ArduPlane V4.3.0dev (f9bc7e4). Displayed on DJI FPV OSD.

Today the devs fixed it...you can build a 4.4.0 dev from the builder without this issue😉