Err Msg: HTTP Error 500-12 Application Restarting

When a client attempts to connect to a Microsoft Internet Information Services (IIS) application that is restarting, the browser displays the following error message:

This message is harmless and usually disappears after the browser is refreshed. There is no good workaround once the message appears from a production environment. However, if the message appears for an extended period of time, you may want to consider stopping all the Web services and reloading the application.

When certain changes are made to an IIS 5.0 application, those changes are committed to the Global.asa file for the application. When you save changes to the Global.asa file, the server finishes processing all of the current application requests before it recompiles the Global.asa file. During that time, the server refuses additional requests and returns an error message stating that the request cannot be processed while the Web site is restarting.

After all of the current user requests have been processed, the server deletes all active sessions, calling the Session_OnEnd event for each session it deletes, closes the application, and then calls the Application_OnEnd event. The Global.asa file is then recompiled.

Subsequent user requests will start the application and create new sessions, and trigger the Application_OnStart and Session_OnStart events. When you view an ASP page while the application is running Application_OnStart, the following error message occurs:
The message is harmless and usually disappears when you refresh the page in your browser.

This error message may also be caused by anti-virus or backup software. When these software packages scan an IIS Web application, IIS may behave as if the Global.asa file has been modified and may therefore restart the Web application. Turning off backup software and virus scanning on the Global.asa file may help resolve this issue. If a client GET request is made during this time, the web server will return a 500-12 error. For additional information on the same error message occurring in Site Server 3.0, Commerce Edition, click the article number below to view the article in the Microsoft Knowledge Base: