This is what I found on microsoft' s site:
Windows Update error 800f0826 is displayed when an update for Windows has failed to install and is preventing you from installing additional updates. Error 800f0826 does not identify the update that has caused the problem. The update that has caused the problem will display a different error. This problem affects updates for Windows only and does not prevent you from installing or automatically receiving updates for other Microsoft programs, such as the Microsoft Office System.
To prevent error 800f0826, you need to identify the update that is causing the problem (it will display a different error), fix the problem, and then try installing updates again. Here's how:
1. Open Windows Update by clicking the Start button , clicking All Programs, and then clicking Windows Update.
2. In the left pane, click View update history.
3. Find an update for Windows that has failed to install, and then double-click the update to view more information.
Updates that have failed to install will display Failed under Status, next to the update name.
4. In the Windows Update dialog box, next to Error details, review the error code for the failed update. If the description contains error 800f0826, click Close, and then repeat steps 3 and 4 until you identify an update for Windows that displays a different error code.
5. Follow the links in the Windows Update dialog box under More Information or Help and Support to try to fix the problem, and then try installing updates again by using Windows Update in Control Panel.
If you could not find an update for Windows that failed because of an error other than 800f0826, or if the problem persists after you have followed the steps above, an error in another area of the operating system might be preventing you from installing updates. To request support by e‑mail, go to the Windows Update Support Center website.
Help and Support search term: WindowsUpdate_800f0826
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