If you enter your WordPress website and you encounter an error like this:

It is due to a failure in the update of the WordPress toolkit extension on your server with Plesk. The solution is to enter via ftp or Plesk file manager and delete a file that will be inside httpdocs called: .maintenance, that is in the path: httpdocs/.maintenance

In case of having many websites with the same problem, ProfesionalHosting has created a script to solve it massively, open a ticket and we will execute it on your vps.