I found another topic with karaf logging errors:
However, in my case (oficial docker container) userdata is in /openhab/userdata
so config file, which was magically emptied, was in /openhab/userdata/etc/org.ops4j.pax.logging.cfg, (that caused problems in karaf, when launching command that operates on logs)
Fortunately, I found file with proper content: /openhab/userdata/org.ops4j.pax.logging.cfg so copied it to emptied /openhab/userdata/etc/org.ops4j.pax.logging.cfg file and it worked…
Hope, that will save somebody from reinstalling whole openhab 