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How to fix 0x800f081f when DISM or .NET cannot find source files

This appears when DISM RestoreHealth or an optional feature like .NET Framework 3.5 cannot find the source files it needs. The fix is to give it a valid source from matching install media. Jump to your situation below or work through the methods in order.

By Neeraj Singh ~8 min Updated Jun 2026 90% found this helpful
Error message
0x800f081f CBS_E_SOURCE_MISSING. The source files could not be found. Use the Source option to specify the location of the files.
Summary

0x800f081f (CBS_E_SOURCE_MISSING) appears when DISM /RestoreHealth or enabling an optional feature such as .NET Framework 3.5 cannot find the source files it needs. By default Windows fetches those files from Windows Update or, on a managed PC, from WSUS. If the component store is damaged and those sources are unreachable or do not have the payload, the operation fails with this code. The reliable fix is to supply the source yourself: mount an ISO of the exact same Windows build and point DISM or the feature install at its install.wim or sxs folder with the /Source and /LimitAccess options. The single most common mistake is using media of a different build or edition than the installed system, which still fails.

What this error means

When DISM repairs the component store, or when Windows enables an optional feature, it needs the original files for those components. Windows tries to download them from Windows Update or WSUS. 0x800f081f means it could not get them: the store is damaged and the online source is missing the payload or is unreachable.

The answer is to stop relying on the online source and hand Windows the files directly from installation media. An ISO of the same build contains every component, so pointing the operation at it with /Source resolves the error, as long as the media matches the installed edition and build exactly.

Common causes

The component store is damaged and Windows Update cannot supply the files.
The PC is managed by WSUS, which does not have the payload.
There is no internet connection to reach Windows Update.
The source media is a different build or edition than the installed OS.
A Group Policy blocks downloading repair content from Windows Update.
The optional feature payload was removed from the image.
Corrupt CBS manifests in the component store.
Expert insight

“0x800f081f is Windows saying I need the original parts and I cannot find them. The cure is to stop arguing with Windows Update and just hand it the files. I mount an ISO of the exact same build, point DISM at install.wim with /Source and /LimitAccess, and it repairs in one pass. The trap that catches everyone is the build, if you grab any old Windows ISO it will still fail, the media has to match the version that is installed.”

Neeraj Singh
Manager, Tech Support & Operations · 19+ years fixing Windows and system errors

✓ How to fix it

Method 1

Point DISM at a matching ISO

1Download and mount an ISO of the exact same Windows build, then run, adjusting the drive letter:
DISM /Online /Cleanup-Image /RestoreHealth /Source:wim:D:\sources\install.wim:1 /LimitAccess
2/LimitAccess tells DISM to use only your source, not Windows Update.
3If install.wim is install.esd, use /Source:esd:D:\sources\install.esd:1.
Method 2

Enable .NET 3.5 from media

1For the .NET Framework 3.5 feature, point it at the sxs folder on the same media:
DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /Source:D:\sources\sxs /LimitAccess
2This installs the feature offline without needing Windows Update.
Method 3

Match the build and edition

1Confirm the ISO is the same edition (Home/Pro) and the same build number as the installed system.
2Check your build with winver and use media that matches.
3A mismatched source is the most common reason this still fails.
Method 4

Bypass WSUS for the operation

1On a managed PC, WSUS may not hold the payload.
2Temporarily allow the device to reach Windows Update, or use the media source above, then repair.
3Ask your administrator if policy blocks it.
Method 5

Allow repair content in Group Policy

1Open Group Policy, Computer Configuration, Administrative Templates, System, and find Specify settings for optional component installation and component repair.
2Enable it and tick to download repair content from Windows Update, or set a source path.
3Then retry.
Method 6

Confirm the store is healthy

1After the source repair, run SFC /scannow to confirm system files are intact.
2Then retry the original feature install or update.
3The store should now have what it needs.

0x800f081f is a missing-source problem, so the fix is to supply the files from media rather than relying on Windows Update. Mount an ISO of the exact same build and use /Source with /LimitAccess. The one thing that trips people up is build mismatch, so check winver and match the edition and build before you point DISM at the media.

Frequently asked questions

What does error 0x800f081f mean?
CBS_E_SOURCE_MISSING means DISM or an optional feature install could not find the source files it needs, because the component store is damaged and Windows Update or WSUS cannot supply them.
How do I fix it with install media?
Mount an ISO of the same Windows build and run DISM RestoreHealth with /Source pointing at install.wim and /LimitAccess, so it uses your media instead of Windows Update.
How do I enable .NET 3.5 with this error?
Point the feature install at the sxs folder on matching media: DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /Source:D:\sources\sxs /LimitAccess.
Why does it still fail with media?
Almost always a build or edition mismatch. The ISO must be the same edition and build as the installed system. Check your build with winver and use matching media.
Does WSUS cause this?
It can. A WSUS-managed PC may not have the repair payload. Temporarily allow the device to reach Windows Update, or use media, then run the repair.
What is /LimitAccess for?
It tells DISM to use only the source you specify and not try Windows Update, which is what you want when the online source is the thing that is failing.

Still not working?

If DISM still reports a missing source with matching media, the component store itself may be too damaged for an in-place repair. As a last resort, an in-place upgrade install (running setup.exe from the same-build ISO and choosing to keep files and apps) rebuilds the store. You can also submit your error to us for a tailored fix.

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