Access error when enabling user database

[Lakrimar]

I just wanted to enable authentication by userdb but when I access the website I get an http-500 error. The logfile contains the following information:

calibre server listening on 127.0.0.1:4711
OPDS feeds advertised via BonJour at: 127.0.0.1 port: 4711
Unhandled exception in state: State: _job_done Client: 127.0.0.1:58696 Request: GET /calibre/interface-data/books-init?library_id=calibre-library&sort=timestamp.desc&1531057863804 HTTP/1.1
Traceback (most recent call last):
  File "site-packages/calibre/srv/loop.py", line 569, in tick
  File "site-packages/calibre/srv/loop.py", line 307, in _job_done
  File "site-packages/calibre/srv/pool.py", line 35, in run
  File "site-packages/calibre/srv/http_response.py", line 441, in run_request_handler
  File "site-packages/calibre/srv/routes.py", line 305, in dispatch
  File "site-packages/calibre/srv/auth.py", line 258, in __call__
  File "site-packages/calibre/srv/auth.py", line 296, in do_http_auth
  File "site-packages/calibre/srv/auth.py", line 252, in check
  File "site-packages/calibre/srv/users.py", line 139, in get
  File "site-packages/calibre/srv/users.py", line 80, in conn
CantOpenError: CantOpenError: unable to open database file

The access works flawless without authentication. I tried to change the permissions on the metadata.db but this doesn't change or solve the problem.

[Lakrimar]

Ok, just ignore it - got it up and running. Maybe it was a folder permission which was not set properly