My persistent 500.24 error

Because of my client's NT trust relationships my websites need to use NT credentials impersonation quite frequently and I keep falling into the same trap when setting up impersonation in IIS7 (rather than IIS6, which I was kind-of used to).

I build and push out the website and then try to access a diagnostic page (which shows the current website's users credentials as understood by the web server) and get the error:

"HTTP Error 500.24 - Internal Server Error An ASP.NET setting has been detected that does not apply in Integrated managed pipeline mode"

A couple things will float up in my mind right then -- I know that in IIS6 and older versions of IIS I always put "impersonate=true" into the web.config file and this causes problems with the new pipeline mode of IIS7.  I'll knock this line out of the web.config file and it won't help -- the 500.24 error will disappear but impersonation is gone.

Then something will happen to throw me into a blind panic (usually a required demo in ten minutes or some other "show and tell" nonsense that means I've got to get this resolved fast) and I'll start flailing around trying to fix it.  I always do, but I want much less stress in my life -- so here are the basic steps again as a reminder so the experience can be shorter next time:

- Go into IIS7 manager and reset the website's application pool to use the "Classic" pipeline
- Modify the web.config file to include:

<system.webServer>

   <validation validateIntegratedModeConfiguration="false"/>

</system.webServer>

 

 See these links for more (and better) information:

http://allen-conway-dotnet.blogspot.com/2010/11/how-to-use-impersonation-in-aspnet.html

 

http://mvolo.com/breaking-changes-for-aspnet-20-applications-running-in-integrated-mode-on-iis-70 

(The latter has a nice section that explains this error very well.)