This article describes the System Update Readiness Tool for Windows Vista-based computers. Microsoft released the System Update Readiness Tool to resolve certain conditions that could cause installing updates and other software not to work. You do not have to manually run this tool. This tool is offered automatically through Windows Update to computers that have a condition that the tool could resolve.

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Update information

After you download the System Update Readiness Tool, it runs a onetime scan for inconsistencies that might prevent future servicing operations. This scan typically takes less than 15 minutes to run. However, the tool might take significantly longer on some computers. The Windows Update progress bar is not updated during the scan, and progress seems to stop at 60% complete for some time. This behavior is expected. The scan is still running and you should not cancel the update.

The System Update Readiness Tool is available from the Windows Update Web site. To obtain this update, follow these steps:

1.	Click Start , click Control Panel, and then click Security.
2.	Under Windows Update, click Check for updates. Important This update is offered on Windows Update only to computers that have a condition that the tool could resolve.

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What is the System Update Readiness Tool?

System resources, such as file data, registry data, and even in-memory data, can develop inconsistencies during the lifetime of the operating system. These inconsistencies might be caused by various hardware failures or might be caused by software issues. In some cases, these inconsistencies can affect the Windows servicing store, and they can cause software updates not to work. The System Update Readiness Tool tries to resolve these inconsistencies.

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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.

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

The following table lists error messages that you might receive when you try to install a software update. These errors might be caused by a system irregularity that the System Update Readiness Tool might be able to resolve. However, the tool might be unable to fix all instances in which these errors occur.

Code	Error	Description
0x80070002	ERROR_FILE_NOT_FOUND	The system cannot find the file specified.
0x8007000D	ERROR_INVALID_DATA	The data is invalid.
0x800F081F	CBS_E_SOURCE_MISSING	The source for the package or file not found.
0x80073712	ERROR_SXS_COMPONENT_STORE_CORRUPT	The component store is in an inconsistent state.
0x800736CC	ERROR_SXS_FILE_HASH_MISMATCH	A component's file does not match the verification information present in the component manifest.
0x800705B9	ERROR_XML_PARSE_ERROR	Unable to parse the requested XML data.
0x80070246	ERROR_ILLEGAL_CHARACTER	An invalid character was encountered.
0x8007370D	ERROR_SXS_IDENTITY_PARSE_ERROR	An identity string is malformed.
0x8007370B	ERROR_SXS_INVALID_IDENTITY_ATTRIBUTE_NAME	The name of an attribute in an identity is not within the valid range.
0x8007370A	ERROR_SXS_INVALID_IDENTITY_ATTRIBUTE_VALUE	The value of an attribute in an identity is not within the valid range.
0x80070057	ERROR_INVALID_PARAMETER	The parameter is incorrect.
0x800B0100	TRUST_E_NOSIGNATURE	No signature was present in the subject.
0x80092003	CRYPT_E_FILE_ERROR	An error occurred while Windows Update reads or writes to a file.
0x800B0101	CERT_E_EXPIRED	A required certificate is not within its validity period when verifying against the current system clock or the time stamp in the signed file.
0x8007371B	ERROR_SXS_TRANSACTION_CLOSURE_INCOMPLETE	One or more required members of the transaction are not present.

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Information for advanced users

Microsoft Download Center

You can manually download the System Update Readiness Tool from the Microsoft Download Center. The following files are available for download from the Microsoft Download Center:

Windows Vista

Windows Vista for x64-based systems

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

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For more information, click the following article number to view the article in the Microsoft Knowledge Base:

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