I spent many hours trying to figure out why I was getting an HttpException message about "Cannot use leading .. to exit above the top directory" in the System.Web.Util.UrlPath.ReduceVirtualPath function.  There was absolutely no where in my code the use of "..".  This was only a problem on ASP.NET 2.0 using IIS6 and only in production code, would not have a problem in debug code.


Well, it turns out that for certain user agents (mostly search engines such as the Google Bot), that the Url RewritePath() function would generate a "../url" in the Form action target and was causing the error.

Does not appear to be a fix at the time of this posting, but there are work arounds.  Also, have not tested on .NET 3.0 to see if the problem still exits.

Here is a link for more information:

http://todotnet.com/archive/0001/01/01/7472.aspx?Pending=true