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0x800F081F

Microsoft Windows

Severity: Moderate

Source: OnlyErrorCodes.com — Every error code. One place.

Windows Error 0x800F081F — Source Files Not Found Fix

What it means

Windows error 0x800F081F means 'The source files could not be found' — it appears when Windows tries to install an optional feature (most often .NET Framework 3.5) and can't reach the payload it needs.
This is documented widely across Microsoft Q&A and Microsoft Learn troubleshoot pages.
The root cause is almost always one of two things: the machine is joined to a WSUS server that doesn't host the payload, or the system files needed for the install were never present (a recent in-place upgrade or a stripped install image).
The fix is Microsoft's DISM command, either pointing at Windows Update directly or at a mounted ISO.

Affected Models

  • Windows 11 (every version)
  • Windows 10 (every version — 1809 onward most commonly affected)
  • Windows Server 2016 / 2019 / 2022 / 2025 — extremely common in domain-joined / WSUS environments
  • Affects feature installations: .NET Framework 3.5, RSAT, language packs, optional features
  • Same fix works across all supported Windows versions

Common Causes

  • Machine is on a WSUS server that doesn't host Features on Demand payloads
  • Group Policy 'Specify settings for optional component installation and component repair' is misconfigured
  • System Component Store (WinSxS) is missing the requested feature files
  • Windows install media isn't accessible (no ISO mounted) when WSUS is the only update source
  • Pending Windows Update is blocking the feature install until it completes

How to Fix It

  1. Try the simplest DISM command first.

    Open Command Prompt as Administrator.
    Run: DISM /Online /Enable-Feature /FeatureName:NetFx3 /All
    This installs .NET Framework 3.5 using Windows Update as the source.
    If the machine has direct internet access and isn't on WSUS, this single command resolves 0x800F081F immediately.

  2. Mount your Windows ISO and use it as the source.

    Download the Windows 11 (or 10) ISO from microsoft.com for your installed version.
    Right-click the ISO > Mount.
    Note the drive letter (let's say D:).
    Open Command Prompt as Administrator and run:
    DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /Source:D:\sources\sxs /LimitAccess
    Replace D: with your actual mounted drive letter.
    This pulls the payload from the ISO instead of Windows Update — the standard fix for WSUS-joined machines.

  3. Fix the Group Policy that's blocking Windows Update.

    Open gpedit.msc (or Local Group Policy Editor).
    Navigate to Computer Configuration > Administrative Templates > System.
    Find 'Specify settings for optional component installation and component repair' > Enable.
    Tick 'Download repair content and optional features directly from Windows Update instead of Windows Server Update Services (WSUS)'.
    OK.
    Then in Command Prompt: gpupdate /force.
    Retry the DISM install — Windows now bypasses WSUS for the feature payload.

  4. Run System File Checker and DISM RestoreHealth.

    If 0x800F081F appears on multiple features (not just .NET 3.5), the Component Store itself may be corrupt.
    Open Command Prompt as Administrator:
    sfc /scannow
    DISM /Online /Cleanup-Image /RestoreHealth
    Both take 10-30 minutes.
    Restart, then retry the feature install.

  5. Make sure pending Windows Updates aren't blocking.

    Open Settings > Windows Update > Check for updates.
    Install everything pending and restart.
    An in-progress update sometimes locks the Component Store from feature installs — completing the pending update clears the block.

  6. For Home edition users without gpedit: use the registry path.

    Windows Home doesn't include gpedit.msc.
    Open Registry Editor (regedit) as Administrator.
    Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU.
    Create a DWORD called UseWUServer with value 0 (zero).
    Restart and retry the DISM install — the machine ignores WSUS and pulls the payload from Windows Update directly.

When to Call a Professional

Error 0x800F081F never needs reinstalling Windows.
If DISM with Windows Update source and a mounted ISO both fail, the Group Policy fix described below points the machine at Windows Update for feature payloads even on a WSUS-joined domain — that resolves the vast majority of corporate cases.

Frequently Asked Questions

I'm not on a domain or WSUS — why am I still getting 0x800F081F?

Two common causes on standalone machines: first, the Windows install was done from a stripped or modified ISO that didn't include the Features on Demand files; second, a recent in-place upgrade left the Component Store in a partial state.
For both, the mounted-ISO DISM command (step 2 on this page) resolves it cleanly — pull the matching Windows ISO from microsoft.com for your installed version, mount it, and point DISM at the sxs folder.
The ISO version must match your installed version (don't use a Windows 10 ISO to fix a Windows 11 install).