0x800F081F 🪟 Windows

Windows Error 0x800F081F: The source files could not be found

DISM or “Turn Windows features on or off” (often .NET Framework 3.5) couldn’t find the files needed to install the feature.

Seen on: Windows

Meaning

Optional features are downloaded from Windows Update or read from installation media. If Windows Update access is blocked (WSUS/Group Policy) or the media version doesn’t match, the install fails with 0x800F081F.

Common causes

  • WSUS/Group Policy prevents downloading from Windows Update
  • Installation media doesn’t match the installed Windows build
  • Corrupted component store
  • Offline machine

⚡ Quick fix

  1. Mount a matching Windows ISO and point DISM at its \sources\sxs folder
  2. Enable “Download repair content directly from Windows Update” in Group Policy
  3. Run DISM RestoreHealth first

Detailed fix by platform

Windows

  1. Install .NET 3.5 from mounted ISO (D:):
    bat
    DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:D:\sources\sxs

How to diagnose

  1. Feature — Which feature is being installed?
  2. Source — Windows Update reachable? Media matches build?
  3. Policy — WSUS/Group Policy restrictions?

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