Note: If Asp does not work, see this article for turning on Classic Asp in IIS 7 and above.
Question: How do you turn on error messages for Classic Asp on IIS 7 and above?
IIS and above, by default, does not return error messages to the browser.
If you are using Windows 7 to do your development, to turn on the error messages and make other changes to IIS, open IIS Manager. To find IIS Manager, in your Start Menu, search for IIS.
Double click the Asp icon so it opens up the properties.
Expand the Debugging Properties.
Set scriptErrorSentToBrowser to True.
You might want to turn on some of the other properties as well, such as enableParentPaths. I did not bother to look up what all the properties did. I just turned on the ones that sounded like they made sense and things seemed to work.
Here is a good reference.