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

Plesk for Windows kb: technical

Applicable to:

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

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

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

Connect to the server via RDP
Open cmd.exe as Administrator and create the password registry entry, specifying a new password:

C:\> plesk sbin psadb -u --password="new_password"
Add the skip-grant-tables option in [PleskSQLServer] section of the file %plesk_dir%MySQL\my.ini:

CONFIG_TEXT: . . .
[PleskSQLServer]
skip-grant-tables
. . .
restart the Plesk SQL Server service:

C:\> net stop PleskSQLServer && net start PleskSQLServer
Change the admin password in the database:

C:\> plesk db "update mysql.user set authentication_string=password('new_password') where user='admin'"
Remove the skip-grant-tables from %plesk_dir%MySQL\my.iniand restart the service again (repeat step #3).
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"