7 steps after installing PostgresQL on Ubuntu Server 20.04


After installation (

sudo apt install postgresql-12) you try to connect to your fresh PostgresQL 12 using 

psql, but it’s responding

psql: error: could not connect to server: FATAL:  Peer authentication failed for user "postgres"


  1. Make sure you’ve run pg_ctlcluster
sudo pg_ctlcluster 12 main start
  1. Check postgres port and change it to 5432 if needed
sudo nano /etc/postgresql/12/main/postgresql.conf

in newer versions it might be 5433 by default, so it causes problems

find a string with 

port = 5433 and change it to 

port = 5432

  1. Restart postgres service (just in case)
sudo service postgresql restart
  1. Sign-in into psql using sudo
sudo -u postgres psql postgres
  1. Set up postgres user’s password. Don’t forget the semicolon!
alter user postgres password 'your_new_password';
  1. Open sudo nano /etc/postgresql/12/main/pg_hba.conf

Change 12 to your porstgresql version

And find a row where you see

local   all             postgres           peer

and change 

peer to 


Make sure that you change the row, some of them look similar


CTRL + O, save the file, and press 

CTRL+X to exit

  1. Start using psql with your new password

Restart the service again

sudo service postgresql restart

and the final step

psql -U postgres --password

then enter the password you’ve created at the third step. You can use these credentials for your apps, too.