How to diagnose and fix the 28000 invalid_authorization_specification error code in Postgres.

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The 28000 error code invalid_authorization_specification in PostgreSQL indicates an issue with user authentication or authorization. This error can occur when login credentials are incorrect, the user does not exist, or the user does not have the necessary permissions to access the requested database or perform the attempted operation.

To diagnose and fix this error, consider the following steps:

  1. Verify Login Credentials: Ensure that the username and password being used are correct. Typographical errors or changes to the user’s password can cause this error.
  2. Check User Existence: Confirm that the user account exists in the PostgreSQL database. An attempt to log in with a non-existent user will result in this error.
  3. Review User Permissions: Make sure that the user has the correct permissions to access the database and perform the required operations.
  4. Examine pg_hba.conf Configuration: PostgreSQL uses the pg_hba.conf file to control client authentication. Verify that this file is correctly configured to allow the user to connect from their current location using the desired authentication method.

Here are examples and sample code to explain and cover the possibilities:

Example 1: Incorrect Login Credentials

-- Attempting to connect to the database with incorrect credentials
psql -U wrong_user -W -d my_database
-- This will raise the 28000 error because the username or password is incorrect.

Fix: Use the correct username and password to connect to the database.

-- Correct connection command
psql -U correct_user -W -d my_database

Example 2: Non-Existent User

-- Attempting to connect to the database with a non-existent user
psql -U non_existent_user -W -d my_database
-- This will raise the 28000 error because the user does not exist.

Fix: Create the user in PostgreSQL or use an existing user to connect.

-- Creating a new user
CREATE USER new_user WITH PASSWORD 'secure_password';
-- Now you can connect with the new user
psql -U new_user -W -d my_database

Example 3: Insufficient User Permissions

-- A user trying to access a database they do not have permissions for
psql -U limited_user -W -d restricted_database
-- This will raise the 28000 error because the user has no permissions for this database.

Fix: Grant the user the necessary permissions.

-- Granting connect permission to the user
GRANT CONNECT ON DATABASE restricted_database TO limited_user;
-- The user should now be able to connect
psql -U limited_user -W -d restricted_database

Example 4: pg_hba.conf Configuration Issues

If the pg_hba.conf file is not configured to allow the user to connect from their host using the specified authentication method, you will encounter the 28000 error.

Fix: Edit the pg_hba.conf file to include a line that allows the user to connect from the appropriate host with the correct authentication method. For example:

# TYPE  DATABASE        USER            ADDRESS                 METHOD
host    my_database     my_user         192.168.1.100/32        md5

After editing the pg_hba.conf file, you must reload the PostgreSQL server configuration for the changes to take effect.

-- Reloading the configuration without restarting the database server
SELECT pg_reload_conf();

When you encounter the 28000 error, carefully check the user’s credentials, existence, and permissions, as well as the pg_hba.conf file’s configuration. Ensure that everything is set up correctly for the user to authenticate and connect to the desired database. For more detailed information on authentication and authorization in PostgreSQL, you can refer to the PostgreSQL documentation on client authentication.

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