Plesk login page displays error: DB query failed: Unknown error

Plesk for Windows kb: technical ABT: Group B

Applicable to:

Plesk login page shows one of the following error:

PLESK_INFO: ERROR: PleskMainDBException
DB query failed: Unknown error
PLESK_INFO: ERROR: Exception: Unable to get administrator password: Can't decrypt data
PLESK_INFO: ERROR: Exception: Unable to get administrator password: The system cannot find the file specified. (Error code 2)

Plesk administrator password in the Windows registry and/or Plesk SQL Server administrator password in the mysql database are corrupted/incorrect.

Automatic Solution (Recommended)

Download the PowerShell script to a Windows server.
Unzip the file.
Right-click on the file "plesk178-admin-pass-reset.ps1" and click "Run with PowerShell" to run the script.

Manual Solution

Create the psa_root user with a random password to perform further operations. Normally, this step is not necessary, since it is supposed to be executed during Plesk installation:

C:\> plesk sbin mysqlmng_adm --inject-root
Remove existing admin user from Plesk SQL:

C:\> plesk sbin mysqlmng_adm --del-user --user-login=admin
Create new admin user with random password:

C:\> plesk sbin mysqlmng_adm --add-super-user --login=admin --password=new_password --allowed-host=localhost

C:\> plesk sbin psadb -u --password=new_password

Note: in the commands above replace new_password with the required password