Plesk for Windows Server shows 503 Service Unavailable: Cannot read configuration file

Symptoms

• When accessing Plesk, the following error appears in a browser:

  PLESK_INFO: Service Unavailable.
  HTTP Error 503. The service is unavailable.

• The "PleskControlPanel" application pool at IIS Manager > SERVERNAME > Application Pools is stopped. After starting it manually, the application pool stops on the next attempt to open Plesk in a browser.

• The following error message appears in the Event Viewer Application log (Windows Logs):

  PLESK_INFO: The worker process for application pool 'PleskControlPanel' encountered an error
  'Cannot read configuration file due to insufficient permissions
  ' trying to read configuration data from file '?\C:\inetpub\temp\apppools\PleskControlPanel\PleskControlPanel.config', line number '0'.
  The data field contains the error code.

  ---

  PLESK_INFO: The worker process for application pool 'PleskControlPanel' encountered an error
  'Cannot read configuration file
  ' trying to read configuration data from file '\\?\<EMPTY>', line number '0'.
  The data field contains the error code.

Cause

Plesk configuration file PleskControlPanel.config located at C:\inetpub\temp\appPools\PleskControlPanel is corrupted.

Resolution

1. Connect to the Plesk server via RDP.

2. Rename the PleskControlPanel.config file located at C:\inetpub\temp\appPools\PleskControlPanel. This file will be automatically generated on the next attempt to open Plesk.

3. Start Plesk Reconfigurator at Windows Start > All Programs > Plesk.

4. In Plesk Reconfigurator, click Repair Plesk Installation > select Check Plesk Services > click Check.

5. Restart IIS using the following command in a command prompt:

   C:\> iisreset /restart

6. Open Plesk in a web-bowser.