How to Customize HTML Error Messages in ISA Server 2006

This document describes the HTML error messages provided with ISA Server 2006 and how to customize them. It also describes how to create new error messages.

About the HTML Error Messages

Web browser clients sometimes receive error messages in the browser as a result of a Web request. If a Web request error occurs on the client before reaching the Microsoft Internet Security and Acceleration (ISA) Server 2006 computer, the error message is generated by Internet Explorer. For a list of standard Hypertext Transfer Protocol (HTTP) error codes, see HTTP 1.1 error messages.

For Web requests reaching the ISA Server computer, ISA Server includes a set of error messages that can be returned to Web browser clients. ISA Server distinguishes between external and internal client requests.

Editing the HTML Error Messages

You can edit any of the .htm files as required. Remember to back up the original file before making modifications. The error messages matching the language of your version of ISA Server are in the ISA Server installation directory in the directory ErrorHtmls. The error messages for other languages are provided at the ISA Server Download Center. The following syntax is used to identify the files:

  • For internal clients, the files are named Error_number.htm.
  • For external clients, the files are named Error_numberR.htm (where R indicates reverse).

The following table lists the error messages in this folder.

File names Description

64.htm and 64R.htm

The connection to the specified Web server has been lost.


The client has not been authenticated successfully (external client only).


The client has not been authenticated by the proxy server (internal client only).

502.htm and 502R.htm

A connection could not be made to an upstream content server.

504.htm and 504R.htm

An attempt to connect to an upstream server timed out.

1460.htm and 1460R.htm

A connection requested to the specified Web server timed out.

10054.htm and 10054R.htm

The specified destination Web server reset the connection.

10060.htm and 10060R.htm

The specified Web server could not be contacted, and the request timed out.

10061.htm and 10061R.htm

The specified Web server could not establish a connection. This is usually the result of attempting to connect to an inactive service on the server.

11001.htm and 11001R.htm

The specified host could not be found.

11002.htm and 11002R.htm

The DNS name server for the specified host could not be contacted.

11004.htm and 11004R.htm

A host was not found.

12206.htm and 12206R.htm

A proxy chain loop configuration has been detected. This might indicate a proxy configuration problem.

12221.htm and


The client certificate used to establish the SSL connection with the ISA Server computer is not from a trusted certificate authority (CA).

Creating Custom HTML error messages

In addition to modifying existing files, you can create additional HTML error messages that are customized for your organization. There are two default HTML error files in the \ErrorHtmls folder that can be used as templates for creating additional HTML error message pages:

  • DEFAULT.htm (internal clients)
  • DEFAULTR.htm (external clients)

You can edit these default .htm files as you would any HTML page. Save error messages you create with the syntax Errorcode.htm. Edit as follows:

  1. Replace [ERRORNUM] with the appropriate error code.
  2. Replace [ERRORTEXT] with the appropriate error message text.
  3. Replace [SERVERNAME] with the name of the server that returns the HTML page.
  4. Replace [VIAHEADER] with the Via header message string that the ISA Server computer receives.

You can use inline graphics in the form of .gif or .jpg files in your custom HTML error messages. However, these files must be stored in a separate, shared directory on the ISA Server computer and fully qualified URLs must be used in the HTML error message files to point to inline graphics.

After modifying existing messages, or creating new ones, restart the Web Proxy service for changes to take effect.