You receive the "Setup cannot uninstall Windows XP because the necessary registration information is missing" error message when you try to uninstall Windows XP

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SYMPTOMS

When you try to uninstall Windows XP by using the c:\windows\system32\osuninst.exe command, you may receive the following error message:

Setup can not uninstall Windows XP because the necessary registration information is missing.

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CAUSE

This problem can occur for either of the following reasons.

• The Undo folder is not present.
• The Win9xundodirpath and Win9xundointegrityinfo registry values are not present in the following registry key:
  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Setup

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RESOLUTION

To resolve this problem:

1. Verify that the Undo folder is present. The Undo folder has the System and Hidden attributes. To view the Undo folder in the Recovery Console, use the "attrib -sh c:\undo" (without the quotation marks) command. By default, the UNDO folder is in the root folder of drive C.
2. Replace the damaged registry with a functional copy of the registry.

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STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

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MORE INFORMATION

307654  (http://support.microsoft.com/kb/307654/EN-US/ ) HOW TO: Install and Use the Recovery Console in Windows XP

229716  (http://support.microsoft.com/kb/229716/EN-US/ ) Description of the Windows 2000 Recovery Console

307545  (http://support.microsoft.com/kb/307545/EN-US/ ) How to Recover from a Corrupted Registry that Prevents Windows XP

303661  (http://support.microsoft.com/kb/303661/EN-US/ ) Uninstall Windows XP and Revert to a Previous Operating System

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APPLIES TO

• Microsoft Windows XP Professional
• Microsoft Windows XP Home Edition

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Keywords:

kbenv kberrmsg kbprb kbsetup KB313859

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