After upgrade to Parallels Plesk Billing 6.0.0 on WINDOWS server you are unable to log in. Instead of http://server_name/app-modernbill-admin/dashboard.php?action=834
you are redirected to http://server_name/dashboard.php?action=834
and get "The page cannot be found" message.
Please, upgrade to the latest Parallels Plesk Billing where the issue is fixed.