ERROR PleskMainDBException Access denied for user ‘admin’@’localhost’ (using password: YES)

Symptoms

After upgrading Plesk on Windows or after changing the admin password, the following error is shown instead of the Plesk login page:

Access denied for user 'admin'@'localhost' (using password: YES)

Cause

An incorrect password is set for the user admin in the MySQL database.

Resolution

1. Connect to the server via RDP

2. Open cmd.exe as Administrator and create the password registry entry, specifying a new password:

   C:> plesk sbin psadb -u –password=”new_password”

3. Add the skip-grant-tables option in [PleskSQLServer] section of the file %plesk_dir%MySQLmy.ini:

   . . .
    [PleskSQLServer] 
    skip-grant-tables 
    . . .

4. restart the Plesk SQL Server service:

   C:> net stop PleskSQLServer && net start PleskSQLServer

5. Change the admin password in the database:

   C:> plesk db “update mysql.user set authentication_string=password(‘new_password‘) where user=’admin'”

6. Remove the skip-grant-tables from %plesk_dir%MySQLmy.iniand restart the service again (repeat step #3).

7. Run the following commands in Command Prompt to update the password in Windows registry:

   C:> plesk sbin psadb -u –password=”new_password”
   plesk sbin psadb -s –password=”new_password”