postgresql not starting on WSL?

Two weeks ago, I installed Ubuntu 18.04 in the Windows Subsystem for Linux.

In there, I installed PostgreSQL 11 using:

sudo apt-get install postgresql-11

At the time, I could start my PostgreSQL using this command:

sudo -u postgres /usr/lib/postgresql/11/bin/pg_ctl -D /etc/postgresql/11/main -l /var/log/postgresql/postgresql-11-main.log start

So far so good.

Two weeks later, I try to start this PostgreSQL engine using the same command and I get this error:

"FATAL:  could not create lock file "/var/run/postgresql/.s.PGSQL.5432.lock": No such file or directory"

I created that folder and gave it chmod 777 to avoid permission problems.

Then I get:

LOG:  database system was interrupted; last known up at 2019-02-16 17:57:02 STDPANIC:  could not flush dirty data: Function not implementedLOG:  startup process (PID 94) was terminated by signal 6: Aborted

Any idea what might be wrong?