Error message when you access a Web site through ISA Server 2006 or Microsoft Forefront Threat Management Gateway, Medium Business Edition: "HTTP 400 - Bad Request"

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Article ID: 941293 - View products that this article applies to.
Important This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
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SYMPTOMS

When you access a Web site through Microsoft Internet Security and Acceleration (ISA) Server 2006 or Microsoft Forefront Threat Management Gateway, Medium Business Edition, you receive the following error message:
HTTP 400 - Bad Request
This problem may occur when you access a Web site that is published in ISA Server 2006 or Microsoft Forefront Threat Management Gateway, Medium Business Edition. This problem may also occur when you access a Web site through an HTTP access rule that is defined in ISA Server 2006 or Microsoft Forefront Threat Management Gateway, Medium Business Edition.

CAUSE

This problem occurs because ISA Server 2006 and Microsoft Forefront Threat Management Gateway, Medium Business Edition drop HTTP responses and HTTP requests if their HTTP headers contain continuation lines.

RESOLUTION

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To resolve this problem, follow these steps:
  1. For ISA Server 2006, apply hotfix 941297. For more information about this hotfix, click the following article number to view the article in the Microsoft Knowledge Base:
    941297 Description of the ISA Server 2006 hotfix package: August 15, 2007
  2. Click Start, click Run, type regedit, and then click OK.
  3. Locate and then click the following registry subkey:
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\RAT\Stingray\Debug\Web Filters
    Note If the
    RAT\Stingray\Debug\Web Filters
    subkey does not exist, you must create it.
  4. On the Edit menu, point to New, and then click DWORD Value.
  5. Type APPEND_CONTINUATION_LINES, and then press ENTER.
  6. On the Edit menu, click Modify.
  7. In the Value data box, type 1, and then click OK.
  8. Exit Registry Editor.
After you follow these steps, the first continuation line is appended to the main header line. The remaining continuation lines are dropped.

STATUS

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

Properties

Article ID: 941293 - Last Review: August 4, 2008 - Revision: 3.1
APPLIES TO
  • Microsoft Forefront Threat Management Gateway, Medium Business Edition
  • Windows Essential Business Server 2008 Standard
  • Microsoft Internet Security and Acceleration Server 2006 Standard Edition
  • Microsoft Internet Security and Acceleration Server 2006 Enterprise Edition
Keywords: 
kberrmsg kbtshoot kbprb KB941293

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