IIS 7.5 – a breaking change in extensionless URIs handling after Windows Server 2008 R2 SP1 is applied?
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We are experiencing a problem with an application we recently migrated from IIS 6 .net 2.0 to IIS 7.5 .net 4.0 (ASP.Net Web Forms)

The code performs custom rewriting in the global.asax Application_BeginRequest event and uses the HttpContext.Current.RewritePath() method to do the re-writing.

When a bad request (a page which does not exist) with an extension comes in like /kentest/test.blah things are handled properly - IIS properly passes in the custom error page which we re-direct to.

When a bad request comes in without a file extension like /kentest/test then IIS does not properly pass the custom error page. We get caught in a loop rewriting the same /kentest/test over and over until IIS throws a recursion 500 exception.

Any ideas how to solve this and get requests without extensions working?

Others seem to have encountered this issue as this [blog post][1] mentions but no solution is provided.


  [1]: http://netpl.blogspot.com/2011/09/iis-75-breaking-change-in-extensionless.html