"0x8007066A" or "66A" error when you install .NET Framework updates

This problem may be caused by system corruption on your computer. For example, your computer may have corrupted hard disk sectors, or an application may have overwritten the .NET Framework files.
To resolve this issue, try one or more of the following methods in the order they are listed.
  1. To fix MSI software update registration corruption issues automatically, click the Fix it button or link, and then click Run in the View Download dialog box. Then, follow the steps in the Fix it wizard.
    Note: This Fix it does not apply to Windows 8 or Windows RT.

    Note This wizard may be in English only, but the automatic fix also works for other language versions of Windows. If you are not on the computer that has the problem, save the Fix it solution to a flash drive or a CD or DVD, and then run it on the computer that has the problem.

    For more information about how to fix this issue, see How to fix MSI software update registration corruption issues.
  2. Visit Windows Update, and then try to install the updates again. Or, update Microsoft Security Essentials.
  3. Try to reinstall the .NET Framework update.
If the issue is not resolved, go to method 2.
Download the Microsoft .NET Framework Repair Tool to repair the following versions of the .NET Framework, and then reinstall the .NET Framework update:
  • The .NET Framework 4
  • The .NET Framework 3.5 SP1
  • The .NET Framework 3.0 SP2
  • The .NET Framework 2.0 SP2
For more information, see Version 2 of the Microsoft .NET Framework repair tool is available. If the issue is not resolved, or if you are using other versions of the .NET Framework, go to method 3.
To manually download and install the updates, follow these steps:
  1. Open Windows Update or Microsoft Update.
  2. To view your update history, do one of the following, depending on your version of Windows:
    • If you are running Windows 8.1, Windows 8, Windows 7 or Windows Vista, click View update history in the left pane of Control Panel.
    • If you are running Windows XP, click Review your update history in the left pane of Control Panel.
  3. In the list of updates, find the update that contains the error code, and note the Knowledge Base (KB) article number for the update that you want to install.
  4. Go to Windows Downloads.
  5. In the Search Download Center box at the top of the page, type KB and then type the article number for the update.
  6. Press Enter, or click the search icon.

    For example, if the KB article number that’s listed for the update is 123456, type KB123456 in the search box, and then press Enter, or click the search icon. (The search icon looks like a white magnifying glass.)
  7. In the Search Results list, locate the KB article that you searched for, and then go to that article.
  8. Click Download, and then click Save in the File Download dialog box.
    8.Click Download, and then click Save in the File Download dialog box.
  9. In the Save in list, click Desktop, and then click Save.
  10. On your desktop, locate the file that you downloaded, and then double-click the file to install the update.
Note If the update is not needed for your computer, the update will not be installed. If the update still fails with one of the error codes, try Method 4.
Use the .NET Framework Cleanup Tool to uninstall multiple versions of the .NET Framework, and then reinstall the components.

To do this, follow these steps:
  1. Check out the .NET Framework Cleanup Tool User's Guide.
  2. Download the .NET Framework cleanup tool.
  3. When you are prompted, click Open, and then click Extract Now.
  4. In the files that you extracted, double-click cleanup_tool.exe.
    If you are prompted for an administrator password or for confirmation, provide the password, and then click Continue.
  5. In the Do you want to run the .NET Framework Setup Cleanup Utility? message, click Yes.
  6. Click Yes to accept the license agreement.
  7. In the Product to cleanup window, click the list, select .NET Framework - All Versions, and then click Cleanup Now.
    Note The cleanup tool does not let you remove the .NET Framework 2.0 in Windows Vista or later versions of Windows because the .NET Framework is installed as an operating system component.
  8. After the .NET Framework is removed, restart the computer.
  9. Download and install the following components:
    The .NET Framework 1.1

    The .NET Framework 1.1 Service Pack 1 (SP1)

    The .NET Framework 3.5 Service Pack 1 (this will also install the .NET Framework 2.0 SP2 and the .NET Framework 3.0 SP2)
  10. Restart the computer.
  11. Visit Windows Update again, and then check for and install updates.
  12. Try to reinstall the .NET Framework update.

More Information

If this problem is still not resolved, you may have to collect additional logging information so that Microsoft Support can help you troubleshoot the problem. To collect the logging information, follow the steps at How to Enable Microsoft Installer logging and verbose logging to gather additional troubleshooting information before you contact Microsoft Support.

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รหัสบทความ: 2507641 - การตรวจสอบครั้งสุดท้าย: 13 มิ.ย. 2014 - ฉบับแก้ไข: 1