PostgreSQL pg_ctlcluster won't work today I was reconfiguring some stuff on a PostgreSQL 9.4 install on a Debian 8. After being done I typed

# pg_ctcluster 9.4 main restart


as usual, but this time it wouldn't start back up. The error message directed me towards the log of the cluster, which was empty.

# pg_ctcluster 9.4 main start


Didn't work either.
So to track the error down I started the cluster manually with

$ /usr/lib/postgresql/9.4/bin/postgres -d 3 -D /var/lib/postgresql/9.4/main -c config_file=/etc/postgresql/9.4/main/postgresql.conf 


as the user postgres. That worked fine. So the cluster works, the start-up script itself must be the culprit then.
So in hopes to get more detailed error messages I tried to start it like so

# pg_ctcluster --foreground 9.4 main start


which, to my surprise, worked just fine without hiccups.

What can I do about that now? What else is there to check that might throw off the start-up script?
I wouldn't like to modify the pg_ctlcluster script tbh.
Issue solved.
Unknown to me, one member of our team deleted the main log file of the database, because it had grown quite a bit. Apparently it was deleted completely instead of being truncated. Then a new log file was created, but for some reason with the root as owner.
Simply changing the owner back to postgres like so

chown postgres:postgres /var/log/postgresql/postgresql-9.4-main.log


solved the issue.