When running Classic ASP or ASP.Net on a Windows Server 2008 R2 server with IIS, you may want to get more info than a “500 Server Error” page can provide. Here are some settings to help you find out what’s going on…
For Classic ASP Errors
In IIS Manager, select your ASP site, the double-click the ASP icon in the IIS section. The configuration settings for this ASP applications will appear. Open the section for Debugging and make sure the option Send Errors to Browser is set to True. Review other settings while you are here to ensure they match want you want.
For Classic ASP and ASP.NET Errors
Just making the change above seems to work find under IIS on Windows 7 but not Windows 2008 R2. You may need to change one other setting. In IIS Manager, select the ASP or ASP.NET site, the double-click the Error Pages icon in the IIS section (do not confuse with the .NET Error Pages in the ASP.NET section) . The list of error codes and related IIS Error Pages will appear. Select the one for 500 errors and right-mouse, then choose Edit Feature Settings from the popup menu.
The default settings is the third option which only allows detailed errors to be sent to a browser on the same server. Change this setting to the second option labeled Detail errors and then details of your code or script errors will be sent to the browser even if it is a remote quest. If you are using Internet Explorer, also make sure that Show Friendly Errors is not enabled. This is not a problem for Firefox users.