0x800f0991
Moderate
Microsoft · Windows
Windows Update component error preventing updates from installing correctly. The servicing stack encountered an issue processing the update package.
Quick Answer
Error code 0x800F0991 on your Microsoft Windows means: Windows Update component error preventing updates from installing correctly. The servicing stack encountered an issue processing the update package.. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
Likely Causes
How to Fix It
1
Install the latest Servicing Stack Update (SSU) manually: Go to the Microsoft Update Catalog (catalog.update.microsoft.com), search for the latest SSU for your Windows version, download and install it.
2
Run the Windows Update Troubleshooter: Settings > System > Troubleshoot > Other troubleshooters > Windows Update.
3
Reset Windows Update components: Open Command Prompt as Administrator and run these commands in order: net stop bits, net stop wuauserv, net stop cryptsvc, del /f /q %ALLUSERSPROFILE%\Application Data\Microsoft\Network\Downloader\qmgr*.dat, then net start bits, net start wuauserv, net start cryptsvc.
4
Clear the SoftwareDistribution folder: Stop the wuauserv service, rename C:\Windows\SoftwareDistribution to SoftwareDistribution.bak, restart the service.
5
Run sfc /scannow followed by DISM /Online /Cleanup-Image /RestoreHealth.
6
If the issue persists, review the Windows Update log: Open PowerShell as Administrator and run: Get-WindowsUpdateLog — this generates a readable log on your Desktop. Search for the error code to identify which specific component is failing.
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
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