You receive an "HTTP 502 Proxy Error - The ISA Server requires a secure channel connection" error message when you install security update MS05-034 for ISA Server 2000

After you install security update MS05-034 for Microsoft Internet Security and Acceleration (ISA) Server 2000, you no longer have outgoing Internet access. In this scenario, you receive an error message that is similar to the following:

This problem occurs if the following conditions are true:

• You install security update MS05-034 for ISA Server 2000.
• The Basic authentication option is enabled on the outgoing Web proxy listener.

Hotfix information

A supported hotfix is 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 software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if 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. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

You must have ISA Server 2000 Service Pack 2 installed.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

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 tool in Control Panel.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

To work around this problem, you can set the AllowAskBasicAuthOverNonSecureConnection registry entry to a non-zero value. However, this workaround causes ISA Server 2000 to request Basic authentication over HTTP both for incoming Web publishing requests and for outgoing Web proxy requests. We recommend that you use this workaround with caution. For more information about this workaround, click the following article number to view the article in the Microsoft Knowledge Base: The hotfix that is described in Microsoft Knowledge Base article 821724 prevents a request by ISA Server 2000 for Basic authentication over HTTP. ISA Server 2000 makes this request when you select Basic authentication as the authentication method on the relevant Web proxy listener both for incoming Web publishing requests and for outgoing Web proxy requests.

This hotfix was intended to prevent requests for credentials over HTTP only in Web publishing scenarios. After you apply the hotfix in the Microsoft Knowledge Base article 821724, ISA Server 2000 prevents requests for Basic credentials over HTTP only for Web publishing requests. If you do not require Basic authentication for outgoing Web proxy requests, disable Basic authentication on the outgoing Web proxy listener.

For more information about security update MS05-034, visit the following Microsoft Web site: For more information about how to install ISA Server 2004 hotfixes and updates, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the terms that are used to describe software updates, click the following article number to view the article in the Microsoft Knowledge Base: