Background jobs; something fails

I set up NextCloud 12.0.5 onto a new VPS. In the admin panel I added 2 other users. No data is stored in my NextCloud yet.
In the admin panel I see also:
Background jobs: Last runned job: 1 hour ago. May be something fails
(Ok, it’s my translation; I see the error in Dutch).
How can I figure out which error it is.

Kind regards,
Guido van Harten