pgAdmin login issues may occur due to a database connection error. If it is network-related, try the previous solutions and reinstall pgAdmin.

If the problem is related to the user account login credentials, enter the psql session and reset the password using this statement:

ALTER USER username WITH PASSWORD 'new_password';

You may also encounter login issues if the user doesn’t have the LOGIN privilege. To grant one, use the following statement:

ALTER USER username WITH LOGIN;