Upload fails: "avrdude: ser_open(): can't open device"

Development Tools Uploading
1

Continuing the discussion from Avrdude: ser_open(): can't open device "\.\COM12"::

Hi, I am having the same kind of problem using an Arduino Uno. i.e. avrdude: ser_open(): can't open device "\.\COM7": the system cannot find the file specified. No issues with Compile/ Verify. Also on connection, I was prompted with a board update to which I updated the board version to 1.8.3. This problem did not go away even after I restarted my machine.

2

Hi @koofnik_ubk. This error might be caused by having the wrong port selected from the Tools > Port menu in Arduino IDE.

Please perform this experiment to verify that the port you have selected is your Arduino board:

With official boards, the port will be labeled with the board name in the menu (e.g., "COM42 (Arduino Uno)"). In this case, you can be fairly confident that you have identified the port. Select that port from the menu and try uploading again.

With some cheap derivative boards the port will not be labeled. You can positively identify the port using this procedure:

  1. Disconnect the USB cable of the Arduino board from your computer.
  2. Select Tools > Port from the Arduino IDE menus.
  3. Take note of the ports (if any) listed in the menu.
  4. Close the Tools menu.
    :exclamation: The ports list is only updated when the Tools menu is re-opened, so this step is essential.
  5. Connect the Arduino board to your computer with a USB cable.
  6. Select Tools > Port from the Arduino IDE menus. - If a new port is listed in the menu, that is the port of your Arduino board.

If you saw a new port appear at the last step, select that port from the Tools > Port menu and try uploading again.

If this doesn't solve the problem, please reply here on this forum thread with the answers to the following questions:

  • While following those instructions, did you see a port in the Tools > Port menu at step (6) that was not present at step (3)?
  • If you did see a new port, was the upload successful after you selected that port?
1 Like
3

Hi @ptillisch,
I tried your steps listed. In the first place, on the top menu Tools>Port, the Port option was grey off.
However, at the bottom right hand of the menu, the text "Arduino Uno on COM7".

arduino com port 7
arduino com port 71126×1364 12 KB

This should mean that the board has recognised a com port.

4

I just realised there is more to what I observed earlier.
After reconnecting, I now have
(a) a blinking LED 1 (ok, means observed)
(b) a power on LED 3 since I pressed the switch (ok, means observed)
(c) a power on LED 4 for potentiometer value > 512 (ok, means observed)
In the code, I was also supposed to have a step to read user input from serial (between 0 to 255) and write to LED 2. Isn't this supposed to be from Tools>Serial Monitor ? If yes, how did I end up with an error "Board at COM 7 is not available" ?

5

No. It only means that you previously selected COM7 from the Tools > Port menu at some point. It will still show that even if there is no port COM7 on your computer.

Please try this troubleshooting procedure and then report your results in a reply on this forum thread:

:exclamation: This procedure is not intended to solve the problem. The purpose is to gather more information.

  1. Disconnect the USB cable of the Arduino board from your computer.
  2. Open the Windows Device Manager.
  3. Select View > Devices by type from the Device Manager menus.
  4. Open the "View" menu.
  5. If there is a ✓ to the left of the "Show hidden devices" menu item, click on "Show hidden devices" to disable it.
  6. Take note of the contents of the "Other devices" and "Ports (COM & LPT)" sections of the Device Manager tree.
  7. Connect the Arduino board to your computer with a USB cable.
  8. Select Action > Scan for hardware changes" from the Device Manager menus.

Did you see any new device appear in the Device Manager tree after doing this? If so, please tell us where it is located in the tree and what it is named.

You can repeat steps 5-8 multiple times if you are not sure.

6

Actually I went through all the steps you mentioned before I posted the message. It showed that a black text (not grey) for COM 7. But when I repeated the steps after message, the error went away.

7

I'm glad it is working now. Thank you for taking the time to post an update!

Regards, Per

8

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.