Uninstall old drivers first using USBDeview to remove ghost devices.
To see how to properly set up a device for flashing and avoid common connection pitfalls: miracle box port error fix
Go to > Advanced options > Startup Settings > Restart . Press 7 or F7 to "Disable driver signature enforcement." Reinstall your drivers and try Miracle Box again. Uninstall old drivers first using USBDeview to remove
The port error is almost always a driver issue. miracle box port error fix