Microsoft KB Archive/311720

= PRB: MDAC Rollback May Fail on Windows 95, Windows 98, and Windows Millennium Edition =

Article ID: 311720

Article Last Modified on 5/17/2007

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APPLIES TO

 Microsoft Data Access Components 2.6, when used with:  Microsoft Windows 95

 Microsoft Windows 98 Standard Edition

 Microsoft Windows 98 Second Edition

 Microsoft Windows Millennium Edition</li></ul> </li> Microsoft Data Access Components 2.6 Service Pack 1, when used with:  Microsoft Windows 95</li></ul>

 Microsoft Windows 98 Standard Edition</li></ul>

 Microsoft Windows 98 Second Edition</li></ul>

 Microsoft Windows Millennium Edition</li></ul> </li> Microsoft Data Access Components 2.7, when used with:  Microsoft Windows 95</li></ul>

 Microsoft Windows 98 Standard Edition</li></ul>

 Microsoft Windows 98 Second Edition</li></ul>

<ul> <li>Microsoft Windows Millennium Edition</li></ul> </li> <li>Microsoft Data Access Components 2.8, when used with: <ul> <li>Microsoft Windows 95</li></ul>

<ul> <li>Microsoft Windows 98 Standard Edition</li></ul>

<ul> <li>Microsoft Windows 98 Second Edition</li></ul>

<ul> <li>Microsoft Windows Millennium Edition</li></ul> </li></ul>

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This article was previously published under Q311720

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SYMPTOMS
The Dasetup.exe program, when used with the /u switch, may not correctly roll back Microsoft Data Access Components (MDAC) to the previous version. You can verify this by using the Component Checker utility which is available at the following Microsoft Web site:

http://msdn2.microsoft.com/en-us/data/aa937695.aspx

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CAUSE
When the MDAC setup encounters errors during the installation process, the expected behavior is to roll back any files and settings changed during installation to their original configuration. However, a known issue with Windows 95, Windows 98, and Windows Millennium Edition (Me) systems prevents this rollback from occurring correctly.

If certain errors are encountered during MDAC installation (for instance, Msxml3.dll is not registered correctly), the MDAC installation completes and reports success even though the installation was not entirely successful. Because the MDAC state on the computer is not a clean installation, subsequent MDAC rollbacks may fail.

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RESOLUTION
On Windows 95 and Windows 98, you can use Component Checker to reconfigure the MDAC components on a computer as an alternative to the Dasetup.exe rollback method.

There is no workaround on Windows Millennium Edition (Me) if Dasetup.exe rollback fails. In this case, contact Microsoft Product Support Services.

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