How to Fix Windows Update Error 0x800f081f in Windows 10/11

Error 0x800f081f (CBS_E_SOURCE_MISSING) means Windows can’t find the required update files. Follow the simple steps below to get your system back on track.

Quick Checklist

Run the built‑in troubleshooter
Reset the update cache
Repair the CBS store with DISM
Restart and try again

Step‑by‑Step Fix

1️⃣ Run Windows Update Troubleshooter

Open Settings → Update & Security → Troubleshoot → Additional troubleshooters → Windows Update and click Run the troubleshooter. Follow any prompts and restart if asked.

2️⃣ Reset the Update Cache (Command Prompt as Administrator)

net stop wuauserv
net stop cryptSvc
net stop bits
net stop msiserver

ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\catroot2 catroot2.old

net start wuauserv
net start cryptSvc
net start bits
net start msiserver

3️⃣ Repair the CBS Store

Open an elevated Command Prompt (right‑click the Start button → Windows Terminal (Admin)) and run:

DISM /Online /Cleanup-Image /RestoreHealth

Wait for the process to finish (it may take several minutes).

4️⃣ Restart Your PC

A fresh boot lets the repaired store take effect.

5️⃣ Try the Update Again

Open Windows Update or Settings → Update & Security → Windows Update → Check for updates. The error should be gone.

If the error persists: download the specific KB update from the Microsoft Update Catalog, install it manually, then retry the update.

Prevent Future Occurrences

Keep Windows Update turned on and install updates promptly.
Run DISM /Online /Cleanup-Image /RestoreHealth and sfc /scannow periodically.
Maintain at least 10 GB of free disk space.
Ensure a stable internet connection when downloading updates.

That’s it! Your Windows 10/11 system should now be able to download and install updates without the 0x800f081f error.