Internal Server Error (500) - Handle Error in HttpSessionStateModul

Hey,

I do have an asp.net mvc 4.0 application which consumes the Redis SessionState component. The WebApp has also configured in Global.asax.cs the Application_Error Method which refers to the settings in the Web.config in the section <customErrors mode=RemoteOnly>... including <error statusCode 500>

Now the requirement of the customer say: 'If SessionStateServer is not reachable, the user have to linked to a static html-page' So far nothing special.

Now I´m facing the problem that neither

- Server.TransferRequest(...) in Global.asas.cs 'Application_Error()'

- nor the Web.config-Section CustomErrors

executing the link to the static html-page.

Configuring the iis to react on  the Http-StatusCode 500 also failed. If I understand everything right, I am facing the problem that Error-Handling of MVC not working, because the call of a HttpModule already fail and therefore there ist no way Transfer the request or link to a static page from Global.asax.cs within my WebApp.

Any Ideas how to resolve this Issue within asp.net mvc?