Upon trying to open Plesk in your browser you receive the following error:
HTTP Error 503. The service is unavailable.
Plesk uses IIS as a Web server. IIS Advanced Logging or IIS Mod-Rewrite is installed on the server. Third-party ISAPI filters are registered in the PleskControlPanel website as shown in the following screenshot:
Plesk Default application pool crashes several seconds after restart with an error such as :
Log Name: System Source: Microsoft-Windows-WAS Date: 9/29/2009 1:02:52 PM Event ID: 5139 Task Category: None Level: Warning Keywords: Classic User: N/A Computer: Test Description: A listener channel for protocol 'http' in worker process '3768' serving application pool 'PleskControlPanel' reported a listener channel failure. The data field contains the error number.
This is caused by the third-party ISAPI filter configured for the PleskControlPanel website, which cannot run at the same time as the Plesk rewrite filter.
Remove third-party ISAPI filters from PleskControlPanel website configuration and keep only the Plesk rewrite filter as shown in the following screenshot: