@dunlix (and others)
Thanks, the disable plugins suggestion worked. Apparently it was the "sanitize html" plugging that was causing the problem.
Not even sure why we had that still installed.
Thanks all for the troubleshooting help!
I wanted restart nodebb coz can't login (always error about credentials) and I got new error in command line:
[email protected]:~$ ./nodebb restart -bash: ./nodebb: Is a directory
I suspect that these 2 problems are somehow connected. The forum started normally with the usual command ./nodebb start
After that, I swapped the database with a local copy and everything seemed to work fine. I logged in as admin and set up the admin panel, and today I found that I can not log into the forum in another browser.