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Topic: (com port 3 already in use) displayed after upload (Read 9734 times) previous topic - next topic


Usb powers up arduino uno but cannot upload.
"com port 3 already in use" is displayed when i try to upload.
    Im having this problem on my new laptop, everything works fine on my desktop.
           Desktop running XP
           Laptop running WIN 7
Any help would be great, thanks.

Coding Badly

On the previous four laptops I've owned, COM3 is the internal modem.  Are you certain the Arduino is COM3?

Are there any Bluetooth / PDA / mobile phone applications running?


shut down all programs and verified arduino is com 3.
 but no change

Coding Badly

Try this...

  • Unplug the Arduino
  • Start the IDE
  • Load a Sketch
  • Verify the Sketch
  • Connect the Arduino
  • The moment you hear the device insertion tone, click Upload


I reinstalled everything and went through all the steps.
  everything works fine now. Dont know but i think i might have forgot
to choose the uno board in the tools menu.
  Thank you for your suggestions and help, I appreciate it.

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