Microsoft KB Archive/921400

= FIX: Error message when you configure Internet Explorer to use a .pac file and you try to access a Web site that requires Kerberos authentication: &quot;HTTP Error 401&quot; =

Article ID: 921400

Article Last Modified on 11/15/2007

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APPLIES TO


 * Microsoft Internet Explorer 6.0
 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Professional

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SYMPTOMS
Consider the following scenario:
 * You are running Microsoft Internet Explorer 6 on a computer that is running Microsoft Windows XP.
 * You configure Internet Explorer to use a proxy auto configuration (.pac) file.
 * You try to access a Web site that requires Kerberos authentication.

In this scenario, you may receive an error message that resembles the following:

HTTP Error 401 - Unauthorized: Access is denied due to invalid credentials.



Hotfix information
A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Prerequisites
The computer must be running Windows XP Service Pack 2 (SP2) to install this fix.

Restart requirement
You must restart the computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

Hotfix file information
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
The problem does not occur if you do not use a .pac file or if you do not call a scripting API that causes a DNS resolution of the host that you access by using the .pac file.

Keywords: kbhotfixserver kbwinxppresp3fix kbqfe kberrmsg KB921400

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