Avrdude: ser_open(): can't open device "\\.\COM8": Access is denied."

[frustratedsoyabean]

I have no other peripherals connected to my laptop except the arduino nano I have.

This is what the output tab shows me:

PLEASE HELP!!! My im testing my SSD1306 display and all, it works okay on my arduino mega. However, in my arduino nano it is stuck on either denied port access or just stuck on uploading.

[ec2021]

HI @frustratedsoyabean ,

there is a pretty old thread about this issue

https://forum.arduino.cc/t/avrdude-ser_open-cant-open-device-com3-access-is-denied/51583

Reasons found were

• Incorrect board chosen in IDE
• Problem with USB cable
• Missing driver for the specific board
• Serial port conflict between devices
• Tx/Rx pins (Serial) of the board connected to an external device while trying to upload
• ...

Good luck!
ec2021

[MaximoEsfuerzo]

If it is a Nano clone try selecting "old bootloader" option from the "processor" submenu.
And it probably has the CH340 chip for the USB port, you must install the driver.

[ledsyn]

How does that affect the IDE not being able to open COMx?

[ptillisch]

Hi @frustratedsoyabean. This error can occur when the port is open in another application. Only one application can have a serial port open at a time so Arduino IDE can't perform an upload under these conditions.

Check to see whether you have any applications running on your computer that might use the port. If they are, close them and then try the upload again. If you have the Arduino IDE Serial Plotter open, close that as well (even though Serial Plotter shouldn't cause a problem, it can under certain conditions due to a bug in Arduino IDE).

If there aren't any other applications using the port, add a reply here on this forum thread to let us know.