Event ID 5011 — IIS Application Pool Availability

Applies To: Windows Server 2008

Web sites and Web applications depend on the availability of Internet Information Services (IIS) application pools. IIS application pools in turn depend on the Windows Process Activation Service (WAS). If WAS is not running or errors occur during the startup or shutdown of an application pool, Web sites and Web applications may not be available.

Event Details

Product: Internet Information Services
ID: 5011
Source: Microsoft-Windows-WAS
Version: 7.0
Message: A process serving application pool '%1' suffered a fatal communication error with the Windows Process Activation Service. The process id was '%2'. The data field contains the error number.


Diagnose an unresponsive worker process

A worker process that fails to respond may exhibit one of the following symptoms:

  • Ping failure.
  • Communication failure with WAS.
  • Worker process startup time-out.
  • Worker process shutdown time-out.
  • Worker process orphan action failure.

To diagnose a worker process that is failing to respond, refer to one or more of the following resources:


To perform this procedure, you must have membership in Administrators, or you must have been delegated the appropriate authority.

To verify that an application pool has started:

  1. Click Start, click Control Panel, and then click Administrative Tools.
  2. Right-click Internet Information Services (IIS) Manager and select Run as administrator.
  3. In the Connections pane, expand the server node and select Application Pools.
  4. In Features View, the Status column for the application pool will indicate Started if the application pool has started.

IIS Application Pool Availability

Internet Information Services (IIS) 7.0