Description of the System Update Readiness Tool for Windows Vista, for Windows Server 2008, for Windows 7, and for Windows Server 2008 R2

This article describes the System Update Readiness Tool for Windows Vista, Windows Server 2008, Windows Server 2008 R2, and Windows 7.
You may become unable to install updates from Windows Update, due to inconsistencies in file data or registry data. By installing the System Update Readiness Tool, you can resolve these inconsistencies and you will be able to install updates from Windows Update. After the System Update Readiness Tool is installed, install updates again from Windows Update.

There are two methods that can be used to download and install the System Update Readiness Tool. If an error occurs while you run Windows Update or if you want to make sure the System Update Readiness Tool is properly installed, try Method 2.

Method 1: Use Windows Update

To download and install the System Update Readiness Tool, follow the steps below:

1. Click Start
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   , and click Control Panel.
2. If you use Windows 7, click System and Security. If you use Windows Vista, click Security.
3. Under Windows Update, click Check for updates.
4. The System Update Readiness Tool (KB947821) is offered, only when there is a problem that the tool could resolve. Click Install updates.

Method 2: Use the Microsoft Download Center

To download the System Update Readiness Tool from the Microsoft Download Center and install in the following table list:

Note To install the correct version of System Update Readiness Tool, you must know your Windows version.

• To find out which Windows version is installed to your computer, follow these steps:
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  1. Click Start and type msinfo32 in the Start Search or Search programs and files, then press ENTER.
     
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  2. In the OS Nameline, locate which version of Windows is installed to your computer. In System Type line, locate the type of your computer.
     
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The following files are available for download from the Microsoft Download Center:
Note The System Update Readiness Tool scans for inconsistencies in your computer, while it is being installed. It typically takes less than 15 minutes to run the scan, however, the tool might take significantly longer on some environments. Although the progress bar may appear to stop, the scan is still running and you should not cancel the update.

What does the System Update Readiness Tool do?

The System Update Readiness Tool verifies the integrity of the following resources:

• Files that are located under the following directories:
  • %SYSTEMROOT%\Servicing\Packages
  • %SYSTEMROOT%\WinSxS\Manifests
• Registry data that is located under the following registry subkeys:
  • HKEY_LOCAL_MACHINE\Components
  • HKEY_LOCAL_MACHINE\Schema
  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Component Based Servicing

Note This list may be updated at any time.

When the System Update Readiness Tool detects incorrect manifests, files, or registry data, it might replace the incorrect data with a corrected version.

What Windows Update installation errors can the System Update Readiness Tool potentially address?

The following table lists the Windows Update installation errors that you might be fixed by the System Update Readiness Tool. However, the tool might be unable to fix all cases in which these errors occur.

Logging

The System Update Readiness Tool creates a log file that captures any issues that the tool found or fixed. The log file is located at the following location:

• %SYSTEMROOT%\Logs\CBS\CheckSUR.log
• %SYSTEMROOT%\Logs\CBS\CheckSUR.persist.log