Unable to access Plesk and IIS service: Error: Configuration file is not well-formed XML

Symptoms

• Unable to access Plesk and IIS service with the error below:

  CONFIG_TEXT: There was an error while performing this operation.
  Details:
  Filename: \\\\?\\C:\\Windows\\system32\\inetsrv\\config\\applicationHost.config
  Line number: 1517
  Error: Configuration file is not well-formed XML

Cause

The corrupted configuration of the IIS service.

Resolution 

1. Log into the server via RDP.
2. Start a command prompt as an Administrator.
3. Execute the following command to list all IIS configuration backups:
   

   C:\> cd %windir%\System32\inetsrv & appcmd list backup
   BACKUP "CFGHISTORY_0000000054"
   BACKUP "CFGHISTORY_0000000055"
   …
   BACKUP "CFGHISTORY_0000000062"

4. Restore the latest available IIS configuration backup:
   

   C:\> cd %windir%\System32\inetsrv & appcmd restore backup CFGHISTORY_0000000062

   • Note: in case the backup restoration fails with the error below, disable the Read-only attribute for the C:\Windows\System32\inetsrv\config\schema\rewrite_schema file:

     CONFIG_TEXT: ERROR ( hresult:80070005, message:Command execution failed.
     Access is denied.)

5. Restart the IIS service:
   

   C:\> iisreset /restart