PostgreSQL user can not connect to server after changing password

It's possible that you're being bitten by this PgAdmin bug (changelog):

2012-11-28 AV 1.16.1 Date picker controls returns a full timestamp by default, which can cause inadvertent date changes on jobs and role validty dates. Ignore the time part.

This bug has been seen to set password expiry dates far in the past, such as 1/1/1970. In this case the error message when trying to connect is no different than with a wrong password.

You can check these expiry dates with:

SELECT usename,valuntil FROM pg_user;

and if they're wrong, reset them with:

ALTER USER username VALID UNTIL 'infinity';

and upgrade pgAdmin.

The simple thing to do is to log in with psql or pgAdmin and

ALTER USER sam WITH PASSWORD 'new_password';

Now, if you cannot log in with a superuser account you can recover by altering the pg_hba.conf settings for this user and reload the config (sometimes I find this requires restarting the server, but am not sure why).

What you can do is add a line that allows you to log in using the ident (peer in 9.2) method (if you can use a local system account of the same name as the user) for local connections for the user, or (if that is not possible) set to "trust" (very temporarily!). If using trust, set back as soon as possible, since this means "trust that the user is who he/she claims!" and consequently this setting is dangerous to leave enabled outside of immediate recovery needs.

Once you have logged in you can reset the password above.

For Windows variant - I too experienced this nasty bug because of pgAdmin for my Windows x64 install of version 9.2. It left my production paralyzed.

In folder C:\Program Files\PostgreSQL\9.2\data or C:\Program Files (x86)\PostgreSQL\9.**x**\data, you'll find the pg_hba.conf text file.

Find the following lines:

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5

and change METHOD md5 to "trust" like this:

# 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

From Windows>Run type "services.msc" and [enter] find the right PostgreSQL instance and restart it.

Your DB security is now blown wide open! Heed the warning to return it back to md5 after changing the user password expiry time to say year 2099 for all the relevant users.