Re: BUG #16537: could not connect to database although database is running

PG Bug reporting form <noreply@postgresql.org> writes:
> here is /var/log/postgresql/postgresql-12-main.log
> 2020-07-13 18:07:02.049 UTC [1092] FATAL:  could not load server certificate
> file "/etc/ssl/certs/ssl-cert-snakeoil.pem": No such file or directory

> What's wrong with postgresql server?

That error message seems reasonably clear from here.
Evidently your postgresql.conf file contains

ssl_cert_file = '/etc/ssl/certs/ssl-cert-snakeoil.pem'

but there isn't actually any such file on your machine.

How you got into this misconfiguration is harder to guess,
especially if this server used to work.  I think it's
normal for Debian-derived systems to have a file like that,
but I have no idea if Parrot is a Debian clone or not.

Anyway, the quickest route to a fix might be to set ssl = off
in postgresql.conf.  If you do want SSL support, you need to
install a valid certificate file and point ssl_cert_file at it.

Personally I wouldn't use ssl-cert-snakeoil.pem even if I had it;
better to generate your own cert.  See

https://www.postgresql.org/docs/current/ssl-tcp.html

            regards, tom lane