What the update components actually are
Windows Update is not a single process but a pipeline of services and folders. The wuauserv service is the update engine itself, the Background Intelligent Transfer Service (bits) moves downloaded files, and cryptsvc checks the cryptographic signatures of what arrives. Between them they keep a download cache in C:\Windows\SoftwareDistribution and signature catalog data in C:\Windows\System32\catroot2.
When a download is interrupted or a cache entry is written half-finished, the pipeline can keep reusing the bad data: updates hang at a percentage forever, or fail with codes like 0x80070002 or 0x8007000D. Deleting the cache forces Windows to fetch everything again from scratch, which is why a reset fixes so many odd update failures. The reset does not reinstall Windows and does not remove updates that are already installed — it only clears the path new downloads take.
- wuauserv — the Windows Update service that scans, downloads and installs updates
- bits — Background Intelligent Transfer Service, which moves files in the background
- cryptsvc — validates the signatures of update packages
- C:\Windows\SoftwareDistribution — the download cache, often several GB after big updates
- C:\Windows\System32\catroot2 — the folder with signing catalog data
Resetting the components step by step
Open Start, type cmd, right-click Command Prompt and choose Run as administrator; on Windows 11 you can also right-click Start and pick Terminal (Admin). Then stop the services with four commands: net stop wuauserv, net stop bits, net stop cryptsvc and net stop msiserver — the last one matters only when the installer service is busy. Now rename the two cache folders: ren %systemroot%\SoftwareDistribution SoftwareDistribution.old and ren %systemroot%\System32\catroot2 catroot2.old.
If a rename fails with access denied, check that cryptsvc really stopped and try again after a reboot. Restart the services in the same order (net start wuauserv, net start bits, net start cryptsvc), open Settings, go to Windows Update and click Check for updates. Windows rebuilds both folders within a few minutes and downloads everything again.
If the reset does not help
Run the built-in troubleshooter first: Settings, then System, Troubleshoot, Other troubleshooters, and Run next to Windows Update. If the component store itself is damaged, repair it with DISM /Online /Cleanup-Image /RestoreHealth followed by sfc /scannow, and repeat the reset afterwards. For an update that installs and fails on every retry, note its KB number and uninstall it from Update history before trying again.
Keep the .old folders for a week or two; once updates work, delete them to reclaim the space. A reset is also worth doing after freeing space on a nearly full system drive, because a crammed cache folder is a classic reason updates refuse to download. And do not touch the WinSxS folder manually at any step: its contents are hard links that Windows manages itself, and deleting things there breaks the component store.
Questions and Answers
Will resetting Windows Update components delete my files or programs?
No. The reset only rebuilds the update cache — personal files, programs and settings survive, and the visible loss is just the update history list, which starts empty.
Is it safe to delete the SoftwareDistribution folder?
Yes, provided the update services are stopped first — that is exactly what the reset does. Rename it instead of deleting, so you can restore the old cache if something goes wrong.
Why does my update keep failing with error 0x80070002?
That code usually means a file the installer expected is missing, most often because the download cache is corrupted. Stopping the services and renaming SoftwareDistribution fixes the majority of cases.
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