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"Error 0xC000009A applying update operation


After installing Windows 7 Service Pack 1 (SP1), you might receive the following error message on a black screen:
"Error 0xC000009A applying update operation {###} of {###} (\Registry...)"
To resolve this issue, first restore your computer to a point in time before you installedWindows 7 SP1 by using the System Recovery Options menu in Windows. Next, install the update described in this topic. Then, after you've installed the update, try reinstalling SP1.
 Troubleshooting:

Step 1: Restore your computer using the System Recovery Options menu

  1. Remove all floppy disks, CDs, and DVDs from your computer, and then restart your computer using the computer's power button.
  2. Do one of the following:
    • If your computer has a single operating system installed, press and hold the F8 key as your computer restarts. You need to press F8 before the Windowslogo appears. If the Windows logo appears, you need to try again by waiting until the Windows logon prompt appears, and then shutting down and restarting your computer.
    • If your computer has more than one operating system, use the arrow keys to highlight the operating system you want to repair, and then press and hold F8.
  3. On the Advanced Boot Options screen, use the arrow keys to highlight Repair your computer, and then press Enter. If prompted, select the Windows 7installation to be repaired, and then click Next.
  4. Select the language and keyboard input method, and then click Next.
  5. Select the user name of an administrator account, type the password, and then click OK.
  6. In the System Recovery Options dialog box, click System Restore.
  7. In the System Restore dialog box, click Next.
  8. Choose a restore point labeled Windows 7 Service Pack 1.
    If you don't see a restore point labeled Windows 7 Service Pack 1, choose a restore point dated before the installation date of the service pack, and then clickNext.
    If you don't see any restore points, click the Show more restore points check box.
  9. On the Confirm your restore point screen, click Finish, and then click Yes.
  10. Click Restart to restart your computer.

Step 2: Install Update for Windows (KB2534366)


You can get this update by using Windows Update.

  1. Click the Start button Picture of the Start button, click All Programs, and then click Windows Update.
  2. In the left pane, click Check for updates, and then wait while Windows looks for the latest updates for your computer.
  3. If you see a message telling you that important updates are available, or telling you to review important updates, click the message to view and select the important updates to install.
  4. Select the check box for Update for Windows (KB2534366) and for any other updates that you want to install, and then click OK.
  5. Click Install updates, and then follow the instructions on your screen. Administrator permission required If you're prompted for an administrator password or confirmation, type the password or provide confirmation.



Note


Note


  • If Update for Windows (KB2534366) doesn't appear in WindowsUpdate, you might need to install another update first. Check for updates again, install any important updates, and then check for updates again.
  • If you have trouble installing this update, go to the KB2534366 Knowledge Base article on the Microsoft website and follow the instructions to download the update manually.

Step 3: Reinstall Windows 7 SP1

  • After you have installed the update, reinstall SP1. At the end of the SP1 installation process, we recommend restarting the PC immediately when prompted, rather than restarting later.