[This is preliminary documentation and subject to change]

Enabling Detailed Custom Error Messages

IIS features its own set of custom errors that provide more informative or more "friendly" feedback than default HTTP 1.1 error messages. For example, the default HTTP 1.1 404 error message that contains the statement "Object Not Found," is expanded to: "The Web server cannot find the file/script you asked for. Please check the URL to ensure that the path is correct. Please contact the server's administrator if this problem persists." These detailed custom error messages are set by default in the Default Web Site in the IIS snap-in.

To configure detailed custom error messages

In the IIS snap-in, select the Web site, virtual directory, directory, or file in which you want to customize HTTP error messages, and click Properties.
Select the Custom Errors property sheet.
Select the default HTTP error message that you would like to change.
Click the Edit Properties button.
In the Message Type box, select File.
Click Browse and navigate to drive letter:\WINNT\help\iisHelp\common\file name.

Friendly error messages are installed by default to the following location: drive letter:\WINNT\Help\iisHelp\common. The file names are numbers that correspond to the specific HTTP errors; for example, 400.htm, 401-1.htm, and so on.

Custom Errors Install Location - IIS 4.0 to IIS 5.1

If you upgraded from IIS 4.0 to IIS 5.1, and you had previously created your own custom error files or modified the custom error files that IIS 4.0 installed in the drive letter:\WINNT\Help\common directory, your custom error files have been moved to the drive letter:\WINNT\Help\iisHelp\common directory and given a .bak file name extension. You can retrieve your custom errors and reuse them in IIS 5.1. For example, the custom error file 400.htm that IIS 4.0 installed is now named 400.bak and is located in the drive letter:\WINNT\Help\iisHelp\common directory (in addition to the new IIS 5.1 custom error files).