I have an arduino mega 2560 and I'm trying to program it using Arduino IDE 1.8.1. The problem is that I also need to keep open another program that will communicate with the Arduino using the COM port. I usually have to make very small changes to the code with the IDE and then check the results in the program.

However, when the IDE has finished uploading the program it will not release the COM port, and the program I'm using will give me an error message saying "access denied". This is a problem because I want to keep both programs open at the same time.

In fact I could just: make my correction to the code, close the IDE when it has finished, open the program I need, check whether the correction I made was right, otherwise close it again and open the IDE again, but that would take an insane amount of time and it would be quite annoying.

Is there a way to force the Arduino IDE to release the COM port so that other programs could communicate with the Aduino?

2 Answers 2


To force the Arduino IDE to disconnect from the COM port, simply go into the Tools menu, go to Ports and select another COM port.

Alternatively, you can open and then close the serial port monitor (Ctrl+Shift+M then Alt+F4).


This type of problem happens many time with me. Try to disconnect your ARDUINO MEGA from your PC / LAPTOP and then connect it again. It must be solve your problem. If this will not work then restart your PC / LAPTOP and try it out again.

  • disconnecting the arduino right after the upload will cause the IDE to freeze.
    – Mauro F.
    Mar 6, 2017 at 19:20
  • So, first disconnect your arduino and then close IDE. And now open again IDE and connect your Arduino. Try it. Otherwise may be cable fault possible. Try it out with other cable.
    – Hasan
    Mar 7, 2017 at 10:07
  • 1
    I don't think you really understood my question, I've updated to make it more clear.
    – Mauro F.
    Mar 10, 2017 at 17:36

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