error opening serial port com 3 port busy

I am getting this message when trying to upload a sketch to the duinotech nano board. I have had no trouble with the uno r3 board. The upload doesn't complete. I also get the message "stk 500 get sync not in sync.
In device manager under ports i have 2 showing.

  1. arduino uno (com4)
  2. usb serial port (com3)
    Is there a conflict here? should I remove one of the ports in device manager?

Please do this:

  • (In the Arduino IDE) File > Preferences
  • Uncheck the checkbox next to “Show verbose output during: compilation”
  • Check the checkbox next to "Show verbose output during: upload
  • Click “OK”
  • Sketch > Upload
  • After the upload fails, you’ll see a button on the right side of the orange bar “Copy error messages” (or the icon that looks like two pieces of paper at the top right corner of the black console window in the Arduino Web Editor). Click that button.
  • In a forum reply here, click on the reply field.
  • Click the </> button on the forum toolbar. This will add the forum’s code tags markup to your reply.
  • Press “Ctrl + V”. This will paste the upload output between the code tags.
  • Move the cursor outside of the code tags before you add any additional text to your reply.

Have you got Nano selected in your IDE?

If so, some Nano are shipped with the old bootloader.
From the Nano selected you can specify the "old bootloader" and try again.

Tom.. :slight_smile:

Maybe use the Uno to load a new bootloader on the Nano?

  1. arduino uno (com4)
  2. usb serial port (com3)

How many USB ports are plugged into?

I have confused my IDE before and couldn't get a port. So I unplugged the board from that USB and into another. hey, there's my port! If not, worst case, unplug the board and reset the PC then don't plug the board in until after the IDE loads.

So much of programming depends on attention to detail. Take your time trying anything and be deliberate and note-taking if necessary because "just doing things" is a great way to repeat mistakes. The step you forgot you took may be a clue.

Funny, there's an active thread with the same problem nearly identically worded in this section of the forum.

WHY repeat the same answers?

it may be worth checking you are using the correct COM: port associated with each Arduino
goto Control Panel> System> Device Manager expand Port (COM and LPT)
unplug the Arduino devices, plug them back in and note which COM port each device is on
then in the Arduino IDE check Tools> Port has the correct COM port selected

@petercl14, do not cross-post. Do not hijack.