Cannot propagate Web server error messages to browser through Access Gateway

Web server running on IIS with .NET applications. The Web server returns 500 errors in numerous cases, and the error page returned to the browser gives a lot of useful info about the error, including reasons, line of code, stack dump, etc. When the Access Gateway detects this error, it will respond to the browser with a generic 500 internal error and no additional details. The end result is that the client does not have many details regarding what triggered the problem.

Enhancement made to development to allow 500 internal errors pass through the Proxy untouched.

For now, the only option is to customise the existing error pages to handle all the cases for 500 errors.