Paint 3D is a built-in 3D modeling app included in Windows 10, which incorporates features of Microsoft Paint and 3D builder to combine a lightweight hybrid 2D-3D editing experience. If you see the following when launching the app, this post tells you how to fix it.
Fix: Error 0x803F8001 Paint 3D is Currently Not Available
Uninstalling Paint 3D and reinstalling it from the Windows Store ought to fix the problem. Before proceeding, make sure you backup your 3D projects by saving the following folder contents to a different location on your hard drive:
Uninstall & Reinstall Paint 3D
Start PowerShell and run the following command:
Get-AppxPackage Microsoft.MSPaint | Remove-AppxPackage
The above command uninstalls Paint 3D. Now, visit the Paint 3D Windows Store URL and install the app.
That should do it! Regarding the earlier Projects created using Paint 3D, if you don’t see them in the Open menu, close Paint 3D. Then copy the “Projects” folder from the backup to the original Paint 3D’s Application package folder.