Windows Update doesn't work

If updates hang or fail

Read the complete step before making changes. Stop if unsure or if new warnings appear.

Check free space on C: (at least 20 GB)
Press Windows + E and click “This PC” on the left. The free space is under “Windows (C:)”. Around 20 GB is a practical guideline; a major upgrade may require more. If there is a lack of space, use the “Insufficient storage space” instructions.
Restart Windows
Save your open documents. Click Start → Power → Restart. Wait until you can log in again.
Open Settings -> Windows Update -> Check for updates
Press Windows + I. Windows 11: Windows Update → Check for updates. Windows 10: Update and Security → Windows Update. Leave the laptop connected to the power supply and do not interrupt the installation.
Write down KB number and error code if it fails again
Open the update history there. Write down the number with “KB” and the complete error code. A photo of the message also helps; do not publish any personal information.
Use Windows Update troubleshooter
Windows 11: Settings → System → Troubleshoot → Other troubleshooters → Windows Update → Run. Windows 10: Update and Security → Troubleshooting → Additional troubleshooters. Depending on the version, “Request help” opens; follow his questions.
If nothing works: execute DISM and SFC
Only on your own PC and after a data backup: Search for “cmd” in the start menu, select “Run as administrator” and confirm the prompt. First enter DISM /Online /Cleanup-Image /RestoreHealth. Once completed, enter sfc /scannow. Wait for both checks, then restart. If there are error messages, write them down instead of attempting further repairs.