Windows Update Error Codes 0x800B0100 and 0x800B0109 both occur when Windows Update tries to install an update but the required files are either damaged or missing. These errors are common, particularly on Windows 10. For general update problems, see how to troubleshoot Windows updates.
This guide explains the steps to fix them. A related certificate error is covered in Windows update error code 0x800B010A.
How to Fix Error Codes 0x800B0100 and 0x800B0109
Work through these methods in order to resolve either error code.
Here’s how to fix it:
Run an SFC scan
Open Command Prompt as administrator, type sfc /scannow, and press Enter. Following this process typically returns a message that any issues were resolved — if the scan reports damage it couldn’t fix, that points to a deeper system corruption to address with DISM.
Temporarily disable Windows Defender
Click Start, type “Windows Security,” select the app, and switch Real-time protection to Off. Keep in mind that turning off antivirus protection leaves your system more vulnerable to malware, so re-enable it as soon as you’re done testing.
Delete temporary files
A corrupted temporary file can trigger these errors. Press Win + R, type %temp%, and press Enter. Press Ctrl + A to select all items, then delete them. Alternatively, use the Windows Disk Cleanup tool: press Win + R, type cleanmgr.exe, press Enter, select the drive to clean, click OK, and choose the file types to remove. Low disk space can also block updates, as explained in Windows update error code 0x80070070.
Run the Windows Update Troubleshooter
These errors often occur when the Windows folder involved in updating is corrupted or damaged. Go to Start → Settings → Update & Security → Troubleshoot, find Windows Update, and let the troubleshooter run and resolve any issues it finds. If updates still won’t install, read Windows 10 updates fail to install.
Clear the Windows Update download folder
Open File Explorer and navigate to C:\Windows\SoftwareDistribution (or C:\Windows\SoftwareDistribution\Download on some versions). Delete everything inside that folder, then restart your PC and try installing the update again. If the Windows Update service itself is the problem, see Windows update error code 0x80070424.
Reset Windows as a last resort
If the error still persists, resetting Windows may be necessary. Back up your files first — resetting will remove your files and settings during the process. For a wider setup problem, see how to fix a Windows installation error first.
Windows 10: Start → Settings → System → Recovery → Reset PC, then choose your preferred options.
Windows 11: Start → Settings → System → Recovery → Reset PC, then choose your preferred options.
Still Not Resolved?
If none of these steps resolve Error Code 0x800B0100 or 0x800B0109, your PC may be experiencing a deeper Windows issue. You can browse more fixes on our Windows updates page. Our experts are here to assist you — Chat with a specialist — for a proper fix.
We are an independent technical support provider and are not affiliated with, endorsed by, or sponsored by Microsoft.
FAQ
What causes Windows Update Error 0x800B0100 and 0x800B0109?
Both errors occur when Windows Update tries to install an update but finds the required files are damaged or missing, most commonly on Windows 10.
Will clearing the SoftwareDistribution folder delete my files?
No. This folder only holds temporary update files — clearing it doesn’t affect your personal documents or installed applications.
Is it risky to disable Windows Defender temporarily?
Yes, it leaves your system more exposed to malware while it’s off — only disable it briefly for troubleshooting, and re-enable it immediately afterward.
Will resetting Windows delete my files?
Yes, depending on the reset option chosen — back up your important files and settings first, since this should be a last resort after other fixes.
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