Arduino Studio COM Port grayed out problem in Windows – Resolved !

Arduino Studio “COM Port grayed out” problem is the most annoying problem of the IDE.

Comparing with other IDEs from other programming languages, Arduino Studio is not very user friendly.
The most annoying problem that I encountered is the “COM Port grayed out” problem which means that the COM port is grayed out and I can’t select anything.
Even if the device drivers are correctly loaded, and they show up in windows control panel, Arduino Studio cannot see them or it considers that ports are busy.

In the end, I had found a solution which is not the easiest, but is the only one that works.

1. Make sure you have the correct driver for your device and the device shows up in “Device Manager”:

  • For ch340 chips (Chinese Arduino boards):
  • For FTDI chips (FT232RL):
  • For USBasp programmers:

2. When the Serial port menu is greyed out, it means there are no available ports.

These are the steps:

1.  Connect your board

For FTDI board:

  • Connect only the FTDI board to a USB port.
  • Go to Control Panel, under the USB Controllers and find the “USB Serial Converter”
  • Now you know that it is installed correctly
  • connect the FTDI board to Arduino.

For Arduino UNO:

  • Connect the board to the computer using a USB cable

2.  Find your COM port number

  • Go to Control Panel, under the Ports (COM&LPT) and look for your COM number.
  • If you have multiple ports you can right-click on each of them and go to Properties -> Driver and find out which one it is your Arduino

3. Note down the number attached to COM

In my case, it was 4.

4. Find the external preferences file and edit it

  • Open Arduino IDE and go to File -> Preferences
  • At the bottom of the menu, the path to the preferences.txt file is listed.
  • Click on that file or open it in a text editor
  • Close the Arduino Studio IDE
  • Scroll down to – serial. port = COMx. Change the ‘x’ to the number of your port.

5. Reopen Arduino

  • Look at the bottom right corner of the IDE: your port should be listed there.

6. Now you can upload sketches to your Arduino only on that port!

  • The next time you will reconnect the Arduino to PC your port number may change.
  • If your port number changes, you will have to take all these steps from the beginning.