500 internal server error after update


Last night I updated my discourse to the latest. Everything was ok so I slept. Today surprisingly everyone got a 500 internal server error when they wanted to open my forum. It was fixed by a simple reboot.

I checked the log and I saw thousands of errors and warnings. This is the most occurred one:

FATAL: remaining connection slots are reserved for non-replication superuser connections

Now what could be wrong with my setup?