It seems Microsoft has a bug in their ASP.NET RewritePath function.  For some reason it will generate form action tags with leading “../” if a certain user agent is used to access your site (such as the Google Bot and other search engines).  This not only generates the error but returns a 500 error to the browser.  This is also a problem only in the production code.

Oh, the number of hours I wasted trying to find this HttpException with the great description “Cannot use leading .. to exit ta above the top directory“.  I searched for hours and never code find a “..“ in any of my code or the code that VS generated!

Here is a link for more information: