0x803F7001 – No valid Windows license found

Windows cannot find a suitable digital license or valid product key.

Stop if unsure or if a new warning appears. Save your work before changes and ask IT before changing a work device. Never disclose passwords or recovery keys.

Open Settings → System → Activation (Windows 10: Update and Security → Activation). Note edition and complete report.
Check whether the installed edition matches your license, such as Home or Pro. Use the troubleshooting provided there.
If necessary, log in with the Microsoft account associated with the license after changing the hardware. Do not use activation cracks or unknown cheap keys.

Test after each step and stop when the issue is solved. Checkmarks are not permanently saved.