Workshop4 works fine in Windows 10.
This message is likely due to you having an old version of the IDE and upgrading to Windows 10 or after a Windows 10 update.
You can fix this by manually by performing these procedure:
- Open Registry Editor
- Navigate to HKEY_CURRENT_USER\SOFTWARE\4DLabs\Workshop
- Delete the entire Workshop folder/key
- Reinstall Workshop4 using the latest installer