Fatal Error: Peer authentication failed for user "postgres", when trying to get pgsql working with rails.

Problem: Sometimes, we get the following error when trying to make a connection in Rails. 

FATAL ERROR: Peer authentication failed for user "postgres" 

Solution: There are a lot of solutions described below.

 

To changing pg_hba.conf file 

Change the following line

 

local   all             postgres                                peer

To

 

local   all             postgres                                md5

After altering the file, you have to restart your PostgreSQL service.

If you are on Linux, then use the following command.

 

$ sudo service postgresql restart

For Windows

 

Window--> Services--> PostgreSQL-x64-12--> Right clieck cand choose Re-Start option

 

If still, you are facing the same fatal error, then see the following solution.

1- Open the file pg_hba.conf (Location : /etc/postgresql/9.x/main)

2- Change the line

 

local   all             postgres                                peer

     To

 

local   all             postgres                                trust

 3- Restart the server

     For Linux, use the following command

 

$ sudo service postgresql restart

     For the window

 

Window--> Services--> PostgreSQL-x64-12--> Right clieck cand choose Re-Start option

     Login into pSQL and set the password

 

$ psql -U postgres db> ALTER USER postgres with password 'your-pass';

 

    Finally, change the pg_hba.conf from

 

local   all             postgres                                trust

To

 

local   all             postgres                                md5

     Again restart the PostgreSQL Server

trust - No authorization anyone can access the database. Make sure don't leave the pSQL at this mode.

peer - Peer client operating system with the database user name to access it.

md5 - Authorized, Protected by password

Using the Command

If you don't want to change the config file(pg_hba.conf), try the following command to fix the issue.

 

root# su postgres postgres$ psql -U postgres psql (9.3.6) Type "help" for help. postgres=#\password Enter new password: Enter it again: postgres=#

Or use the following

 

sudo psql --host=localhost --dbname=database-name --username=postgres

Also, try the following code in the connection.

 

Use host=localhost in connection. PGconn *conn = PQconnectdb(     "host=localhost user=postgres dbname=postgres password=123" );