Article ID: 942228 - View products that this article applies to.
When a Microsoft .NET Framework 1.1 client application tries to access some resources from Internet Information Services (IIS) 7.0 on a Windows Vista-based computer, an authentication failure occurs. This problem occurs if one of the following conditions is true:
Note This problem does not occur if the .NET Framework 1.1 client application tries to access some resources from IIS on a Windows Server 2008-based computer.
The remote server returned an error: (401) Unauthorized.
at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
at System.Net.HttpWebRequest.GetResponse() at simpleclient.Form1.Button2_Click(Object sender, EventArgs e) in E:\Attempts\simpleclient\Form1.vb:line 123
This problem occurs because of a problem in the .NET Framework. When a client application tries to access some resources from IIS, IIS sends back "WWW-Authenticate" headers to the client application. The headers indicate what authentication schemes are configured for the client-requested resources. When the client application selects Integrated Windows authentication as the authentication scheme, the application sends back a token. Then, IIS sends back a challenge to the token. If other authentication schemes are also defined for the client-requested resources, IIS may send other "WWW-Authenticate" headers together with the challenge in the response. In this case, the .NET Framework client application incorrectly parses the challenge, and the authentication failure occurs.
Note Earlier versions of IIS do not send back other possible authentication schemes for the client application. Therefore, this problem does not occur.
Hotfix informationA supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next .NET Framework 1.1 service pack that contains this hotfix.
To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:
PrerequisitesYou must have the .NET Framework 1.1 Service Pack 1 installed to apply this hotfix.
Restart requirementYou do not have to restart the computer after you apply this hotfix.
Hotfix replacement informationThis hotfix does not replace any other hotfixes.
File informationThe 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.
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To work around this problem, use one of the following methods:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/824684/ )Description of the standard terminology that is used to describe Microsoft software updates
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