How Solve CN900 Mini No Valid COM Port Found Error

Here are the proper causes and solutions to CN900 Mini key programmer “No valid com port is found” error.

Problem:
I tried to update CN900 Mini key copy machine software to new v1.20. But when i connect to computer via USB, it prompted me error message “No valid COM port is found on the computer. Please check CN900-Mini’s power and usb cable”. What’s wrong?

Error causes:
1. You did not well connect CN900 Mini to computer
2. You did not power on the machine after well connect to computer
3.  You did not install mini cn900 driver.