Unable to access Plesk after Plesk upgrade: You do not have permission to view this directory or page

Symptoms

After upgrading Plesk to the next release, instead of the login page the following message is shown:

You do not have permission to view this directory or page

Cause

The upgrade was not completed.

Resolution

1. Connect to the Plesk server via RDP.

2. Start a command prompt as an Administrator.

3. Start Plesk Installer and select the latest available version for upgrade:

   C:> plesk installer --console

4. Follow the installation wizard and proceed with installing the packages that it offers to upgrade.