Get Detailed Error Messages Using IE/IIS7

Situation: You are writing or debugging some web code, and the error you are seeing in the browser is almost, but not quite, entirely useless. It may be pretty though.

Environment: IE6 or 7 on the workstation, Windows Server 2008 and IIS7 on the server.

The first place to look is the browser settings.

1. Click the Tools menu (might have to press ALT first to see it).
2. Click Internet Options.
3. Go to the Advanced tab.
4. Uncheck the box for “Show friendly HTTP error messages”.

The second place to look is in the Error Pages section of IIS:

1. Open IIS Admin.
2. Select a web site.
3. Open the Error Pages tombstone (doesn’t it look like a graveyard of icons?).
4. Click the extremely intuitive Edit Feature Settings link under Actions on the right side.
5. In the Error Responses area, choose your preference.

It is “more secure” to leave the default settings. One argues that you can do your testing with the web browser on the local server, so you only need local requests to return useful error messages. However, you might wonder during your testing whether IE Enhanced Security, UAC, DEP, and other wonderful security settings that you have left on your server are interfering with the operation of your web application. For this reason, you may want to flip this over to “Detailed errors”, at least while you are working on the problem.

Finally, there is one more place to look.
I am uncertain whether this affects only classic ASP code, or ASP.NET as well, but here it is:

1. Select a web site.
2. Double-click the ASP tombstone.
3. Click the “+” sign next to Debugging Properties.
4. Change the “Send Errors to Browser” parameter to “True”.

That should do the trick. See how much easier debugging is now?

Tags: Debugging, Friendly HTTP Errors, IIS7