BUG #16564: Can't start the service postgresql@11-main.service

The following bug has been logged on the website:

Bug reference:      16564
Logged by:          Stemy
Email address:      stemy@stemy.me
PostgreSQL version: 11.2
Operating system:   Debian
Description:

Hello,

I can't use any server app that requires a postgresql database. 

I can't even start the service. It is marked as "inactive (dead)", and if i
execute "systemctl start postgresql@11-main.service", it returns me this:
"Assertion failed on job for postgresql@11-main.service.". 

Here's what a "systemctl status" give:

● postgresql@11-main.service - PostgreSQL Cluster 11-main
   Loaded: loaded (/lib/systemd/system/postgresql@.service; enabled; vendor
preset: enabled)
   Active: inactive (dead)
   Assert: start assertion failed at Thu 2020-07-30 19:13:54 CEST; 1h 21min
ago
           AssertPathExists=/etc/postgresql/11/main/postgresql.conf was not
met

So what have i to do to "resurrect" it ?

Thanks.