In IIS Manager, select your site, double-click the Error Pages icon and click on Edit Feature Settings in the pane on the right. Choose Detailed Errors. If that is not enough, click on the .NET Error Pages in the ASP.NET section, again Edit Feature Settings in the pane on the right, choose Off.

If this is a production machine, change these settings back after you are done with debugging your code.


IIS will, by default, show you detailed errors if you browse via localhost on the web server itself. That might help?