Windows Update error 800b0101

If you receive Windows Update error 800b0101, it means that the security certificate for an update installed on your computer is no longer valid. When Windows Update attempts to install a more current update, it can't.

The System Update Readiness Tool can correct some conditions that cause this error. To use the tool, follow these steps:

  1. Go to the System Update Readiness Tool webpage. In the Information for advanced users section, find the Windows edition and system type of your computer, and then click the link to download the System Update Readiness Tool. To find your edition of Windows, see View your computer information.

  2. Run Windows Update again.


    • Typically, the scan takes 15 minutes or less, but it can take longer on some computers. The Windows Update progress bar is not updated during the scan, and progress can appear to stop at 60% complete. This behavior is expected. The scan is still running and you shouldn't cancel the update.

If the error occurs after you've run the System Update Readiness Tool, you'll need to find and uninstall the update or updates that caused the error. The steps to fix the problem are intended for advanced users. If you're not comfortable performing these steps, ask a friend to help you.

These steps could require you to restart your computer several times, so you might want to print these instructions before following them.

Since the date on the security certificates for these updates has expired, you'll have to also reset the time on your computer to before the expiration date to be able to uninstall them. To do that follow these steps

  1. In Windows, click Start, and then type CheckSUR.log into the search box.

  2. In the results, under Files, click CheckSUR.log to open it in Notepad.

  3. In Notepad, press Ctrl+F to open the Find box.

  4. In the Find box, type 0x800b0101, and then click Find next.

  5. If there are any matches, note the file name associated with the error. The file name will have these characteristics:

    • It will be long

    • It will include the full Windows path

    • It will ends in .cat

    • It will include an element starting with KB followed by six or seven numbers (for example, KB123456)

  6. Open the C:\Windows\servicing\packages folder using Windows Explorer and find the .cat file you noted in step five.

  7. Right click the file, click Properties, and then click the Digital Signatures tab.

  8. Click Details, and then click View Certificate. Under Valid from, note the second date listed (the date the certificate expired). Click OK, click OK, and then click OK again.

  9. Change the date on your computer to before the expiration date noted in the certificate. To learn how to do this, see Set the clock.

  10. Open Installed Updates by clicking the Start button Picture of the Start button, clicking Control Panel, clicking Programs, and then, under Programs and Features, clicking View installed updates.

  11. Find the update identified by the KB number noted in step five, and then click Uninstall. Administrator permission required If you're prompted for an administrator password or confirmation, type the password or provide confirmation.

  12. Run the System Update Readiness Tool, and then follow these steps again for each occurrence of error 0x800b0101 in the CheckSUR.log file.

  13. Run Windows Update again.

If you continue to see this error, see this automatic troubleshooter on the Microsoft Support website, or go to the Microsoft Answers website for more assistance.

Error codes this applies to:

  • WindowsUpdate_800b0101

  • 0x800b0101

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