FATAL: password authentication failed for user "postgres" (postgresql 11 with pgAdmin 4)

I recently installed Postgresql 11, during the installation, there's no step to put password and username for Postgres. Now in pgAdmin 4, I wanted to connect the database to server and it's asking me to input password, and I haven't put any in the first place.

Any one knows what's going on?

The default authentication mode for PostgreSQL is set to ident.

You can access your pgpass.conf via pgAdmin -> Files -> open pgpass.conf

That will give you the path of pgpass.conf at the bottom of the window (official documentation).

After knowing the location, you can open this file and edit it to your liking.

If that doesn't work, you can:

• Find your pg_hba.conf, usually located under C:\Program Files\PostgreSQL\9.1\data\pg_hba.conf

• If necessary, set the permissions on it so that you can modify it. Your user account might not be able to do so until you use the security tab in the properties dialog to give yourself that right by using an admin override.

• Alternately, find notepad or notepad++ in your start menu, right click, choose "Run as administrator", then use File->Open to open pg_hba.conf that way.

• Edit it to set the "host" line for user "postgres" on host "127.0.0.1/32" to "trust". You can add the line if it isn't there; just insert host all postgres 127.0.0.1/32 trust before any other lines. (You can ignore comments, lines beginning with #).

• Restart the PostgreSQL service from the Services control panel (start->run->services.msc)

• Connect using psql or pgAdmin4 or whatever you prefer

• Run ALTER USER postgres PASSWORD 'fooBarEatsBarFoodBareFoot'

• Remove the line you added to pg_hba.conf or change it back

• Restart PostgreSQL again to bring the changes to effect.

Here is an example of the pg_hba.conf file (METHOD is already set to trust):

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# IPv4 local connections:
host    all             all             127.0.0.1/32            trust

# IPv6 local connections:
host    all             all             ::1/128                 trust

NOTE: Remember to change the METHOD back to md5 or other auth-methods listed here after changing your password (as stated above).