Error unable to launch after pncconf.

There are two solutions if you read a few posts back in this thread...

Time to edit manually. comment out the offending line until you can open it, Then use halshow to get the correct pin names and edit your config accordingly

Thank you so much for helping out.
I had to comment out 2 lines:
hm2_5i25.0.dpll.01.timer-us
hm2_5i25_0.stepgen.timer-number

AND I had to disable the "custom GladeVCP GUI panel" to get linuxcnc to start up again.

In the end I could still use "custom PyVCP GUI panel" instead to show the motor speed
So at least the system is now up and running under 2.9.1 (I still have 2.8.4 as backup available)

Again, thank you very much, I hope I did the right things...