How to fix it

0x800f081f shows up during Windows Update or when changing Windows features, and it means the update couldn't find source files it needed. The underlying Windows error is CBS_E_SOURCE_MISSING — the Component-Based Servicing store (WinSxS) is missing or has damaged files.

What it means

Windows keeps a copy of every system file in a folder called the component store (C:\Windows\WinSxS). When it installs an update, it pulls files from there. If files are missing, corrupted, or the store's index is damaged, the update stops with 0x800f081f.

Where you'll usually see it

  • Mid-way through a Windows Update cumulative update
  • When turning a Windows feature on or off (e.g. in Apps → Optional features)
  • After a failed update, when you try to install the same one again

Common causes

  • A corrupted or partial component store (WinSxS)
  • A previous update that failed halfway and left the store inconsistent
  • A disk with bad sectors or a failing drive
  • Antivirus or a disk-cleanup tool that deleted protected files

Quick fixes (try these first)

  1. Run Windows Update troubleshooter — Settings → System → Troubleshoot → Other troubleshooters → Windows Update.
  2. Free up disk space — the store needs headroom; make sure you have at least 10–20 GB free.
  3. Restart and retry once — a clean reboot sometimes lets the store re-sync.

Detailed fixes

The proper repair is to rebuild the component store. From an admin Command Prompt or Terminal, run in order:

`` dism /online /cleanup-image /restorehealth ``

Wait for it to finish (it downloads from Windows Update, so allow 10–30 minutes and a stable connection). Then:

`` sfc /scannow ``

Reboot, then try the update again.

What DISM /restorehealth does: it repairs the Windows image and the component store using files from Windows Update. It does not delete your personal files, apps, or settings. It is the standard, Microsoft-recommended first repair for store problems.
What SFC /scannow does: it scans protected Windows system files and replaces any that are damaged with a clean copy from the store. It is non-destructive — it only replaces files, and only damaged ones.

If repair doesn't fix it — a repair install

If the store is too damaged to repair, the reliable fix is an in-place upgrade (also called a repair install): run the Windows 10/11 setup again from the Media Creation Tool and choose Keep personal files and apps. This rebuilds Windows and the component store while keeping your documents, programs, and settings.

Before you do this: back up anything important. A repair install is designed to be non-destructive, but a backup is the one step that makes it safe.

When to suspect hardware

If you also see disk errors, random file corruption elsewhere, or the drive is old, a failing hard drive or SSD can cause 0x800f081f repeatedly. Run your drive manufacturer's health check (or chkdsk) and watch SMART status. Repeated store errors on a drive that's also throwing I/O errors usually means the drive needs replacing, not just the store.

Related errors

  • 0xC1900107 — Windows could not be installed
  • 0x80004005 — Unspecified error (often appears alongside update failures)
  • 0x80070005 — Access is denied