The peer authentication method in PostgreSQL refers to a type of authentication that relies on the operating system to authenticate the provided user. This requires the PostgreSQL and system users to match for correct authentication.
This tutorial explores the common causes of the “peer authentication failed for user ‘postgres'” error in PostgreSQL.
Common Causes For the Error
Several reasons may cause this error when working in PostgreSQL. These causes include:
Incorrect Operating System User
When logging into the PostgreSQL server using the peer authentication method and the Postgres user does not match the corresponding system user named “postgres”, the peer authentication will fail when connecting to the server.
Incorrect Authentication Method
In some cases, you may have conflicting server authentication methods. For example, if the server is configured to peer but you are using another authentication method, this may result in the mentioned error.
Misconfigured PostgreSQL Server
The PostgreSQL server’s configuration file (typically named postgresql.conf) may have incorrect settings for authentication methods. For example, if the “peer” authentication method is enabled but inappropriate for your setup, it can lead to authentication failures.
Upgraded PostgreSQL Version
When upgrading PostgreSQL, the authentication method for the “postgres” user may have changed. If the authentication method is no longer compatible with the one that is specified in the configuration, it can cause authentication failures.
Common Fixes For the Error
You can try The following common fixes to fix the “peer authentication failed for user ‘postgres'” error.
Fix 1: Switch the Authentication Method
The first attempt that you can make is to switch the server authentication method. For example, you can set the server authentication method of md5 which relies on the username/password combination instead of the OS auth.
Fix 2: Verify the Username and OS User Combination
Next, ensure that you’re logged in with the correct system user that matches the PostgreSQL user that you’re trying to connect with is essential.
For example, if you are logging into the database as the Postgres user, you should be logged in to the system as the Postgres user.
Fix 3: Reset the Password for the Postgres User
Another method that you can try is resetting the password for the Postgres user.
- Switch to the “postgres” system user by running the “su – postgres” command.
- Access the PostgreSQL command line by running the psql.
- Change the password for the postgres user using the following SQL command:
- Exit the PostgreSQL command line by running the \q.
- Restart the PostgreSQL service to apply the changes.
Conclusion
This tutorial explored the “peer authentication failed for user ‘postgres'” error. We discussed the possible causes of this error and the possible solutions that you can take to resolve it.
