I upgraded my Pixhawk 2 to the latest stable PX4 version for the first time in a year or so. After using QGC to do the upgrade, QGC could no longer communicate (via serial over USB) with the Pixhawk. After trying a bunch of things I discovered that removing the /etc/extras.txt file from the sd card fixed the problem.
That file contains the command specified here: https://pixhawk.org/peripherals/telemetry/frsky?&#usage
i.e. frsky_telemetry start -d /dev/ttyS6
I presume the fix for issue #4409 from a year ago would be in stable by now?
Also my symptoms seem more severe than described in that issue, in that the Pixhawk seems to crash or something, rather than just the telemetry failing to work.
I am using a D8R-II plus receiver.
Any help would be greatly appreciated,