Password Authentication Fail Error for Postgres User

When connecting to the PostgreSQL server, you may encounter the “password authentication failed for user ‘postgres'” error. This error occurs when the authentication process fails for the default “postgres” user.

In this tutorial, we will explore the various potential causes of this error and discuss the potential solutions to fix this error.

Potential Causes

There are five major potential causes for this error when connecting to the PostgreSQL server.

These causes include the following:

1. Incorrect Password – The most common cause of this error is an incorrect password for the “postgres” user.
2. Authentication Method Mismatch – The second potential cause of this error is a mismatch between the defined authentication method which is defined for the postgres user and the one that is used in the connection.
3. Case-sensitivity – PostgreSQL usernames are case-sensitive. If you provide the username with a different casing (use lowercase), PostgreSQL will fail to authorize the connection.
4. Invalid Configuration – Incorrect configuration settings in the PostgreSQL configuration files can cause authentication failures.
5. Connectivity Issues – Network or firewall settings might prevent the connection to the PostgreSQL server.

The given details are some of the potential causes for the error that we discussed earlier. Next, let us look at some potential solutions to fix them.

NOTE: Some of the solutions that are discussed here may require admin permissions on the server. Hence, ensure that you have administrative access to the PostgreSQL server.

Solution 1: Check the Password and Username Casing

The first and most common method is to ensure that the casing for both the username and the password is correct.

The connection command is as follows:

NOTE: The username is in lowercase, while the -U parameter is in uppercase.

Running the given command should prompt you for the postgres user’s password. Provide the password that you configured during the server installation.

If the login fails despite the correct username and password, proceed to the next solution to learn more.

Solution 2: Configure the Authentication Method

The next solution is to change the authentication method for the Postgres user. Locate the “pg_hba.conf” file. You can find this file either in the data directory (Windows) or in the main directory (Linux).

Edit the file with your text editor and locate the following entry:

By default, the entry should have the authentication method set to “peer” or “ident.” Change it to “md5” for password-based authentication.

Save the file and restart the server to apply the changes. You can then attempt to connect with the set password for the Postgres user.

Solution 3: Verify the Configuration Settings

The next step is to ensure that PostgreSQL allows connections from your address. Follow the steps as defined in the following:

1. Open the PostgreSQL configuration file, “postgresql.conf”, using your favorite text editor.
2. Locate the listen_addresses parameter and ensure that it allows the IP address or hostname that you are connecting from.
3. Similarly, verify that the port parameter matches the port that you use for the connection.
4. Save the changes to the file and restart the PostgreSQL server.

Conclusion

We covered the causes of the “password authentication failed for user ‘postgres’” when connecting to the PostgreSQL server using the Postgres user. We also explored some potential solutions to this error.