Ahh! Thx man! Had the same stupid "... unexpectedly ..." error with Claymore mining lbry in the background.
After stopping it it worked.

Btw. If you do it the other way around (first starting the Lbry app and then Claymore) Claymore will report:
server: bind failed with error: 10048 (port for remote management is busy, use different -mport value), next attempt in 20sec...