Note the KB number of the failing update in Settings > Windows Update > Update history. If the same code appears in another program (for example backup or an app installer), the file it cannot find is specific to that program. If Windows cannot start, see the startup guide.
Work through these checks
0 of 7 complete01Restart and run the troubleshooter
A restart finishes pending updates, and the troubleshooter resets update settings.
- Restart the PC with Restart (not Shut down) and check for updates again.
- On Windows 11, open Settings > System > Troubleshoot > Other troubleshooters and select Run next to Windows Update.
The update installs.
If it does not helpIf it fails again, continue with step 2.
02Free up disk space
An update that runs out of space can leave incomplete files behind.
- Open Settings > System > Storage and use Cleanup recommendations.
- Microsoft notes that quality updates typically need 2–3 GB or more of free space, and feature updates 6–11 GB or more.
Enough space is free on drive C:.
If it does not helpThe 0x80070070 guide on this site covers freeing space in detail.
03Clear the Windows Update cache
Removing the damaged download cache makes Windows download the update files again.
- Open Command Prompt as administrator and run net stop wuauserv, net stop bits and net stop cryptsvc.
- Run ren %systemroot%\SoftwareDistribution\Download Download.bak, ren %systemroot%\SoftwareDistribution\DataStore DataStore.bak and ren %systemroot%\system32\catroot2 catroot2.bak.
- Run net start cryptsvc, net start bits and net start wuauserv, then check for updates.
Use Command Prompt, not PowerShell, for these commands.
The update downloads fresh and installs.
If it does not helpThe update history may look empty afterwards; installed updates are not affected.
04Repair system files with DISM and SFC
Microsoft's fix for Windows Update corruption errors is DISM followed by SFC.
- In Terminal (Admin), run DISM.exe /Online /Cleanup-image /Restorehealth.
- Run sfc /scannow, restart and try Windows Update.
DISM and SFC complete and the update installs.
If it does not helpIf DISM fails, see the 0x800F081F guide on this site.
05Check security software
Security software can quarantine or block files that an update needs.
- Check Windows Security > Virus & threat protection > Protection history, and your third-party antivirus quarantine, for Windows files.
- Temporarily pause third-party antivirus and try the update again.
The update installs.
If it does not helpTurn protection back on afterwards.
06Install the update manually
A manual download from the Microsoft Update Catalog contains all the files the update needs.
- Search for the KB number on the Microsoft Update Catalog (catalog.update.microsoft.com).
- Download the version for your system (usually x64) and run the .msu file, then restart.
Download updates only from Microsoft.
The update installs.
If it does not helpIf it fails too, continue with step 7.
07Repair Windows with an in-place upgrade
An in-place upgrade replaces all system files while keeping your files and apps.
- Download the Windows ISO for your version from Microsoft and mount it.
- Run setup.exe and choose to keep personal files and apps.
Back up important files before starting.
Windows is repaired and updates install.
If it does not helpRun Windows Update afterwards.
Possible causes
- An interrupted or incomplete update download
- Damaged Windows Update cache (SoftwareDistribution)
- Damaged system files or component store
- Too little free space for the update
- Security software removing update files
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