Port is busy during file system upload

[abaymar]

I cannot upload files as Arduino IDE complains that the port is busy and gives a fatal error:

A fatal esptool.py error occurred: [Errno 16] could not open port /dev/cu.usbserial-0001: [Errno 16] Resource busy: '/dev/cu.usbserial-0001'

The only solution I found is this:

• Select an incorrect port, for example: "/dev/cu.wlan-debug" in Arduino IDE Tools/Port
• Start sketch uploading and wait until the upload procedure becomes blocked, but not until it times out
• Select the correct port (that is the one with the ESP attached, in my case: "/dev/cu.usbserial-0001") in Arduino IDE Tools/Port
• Upload the files
• Upload the sketch if needed

MacBook Air M1 Arduino 2.2.1 ESP8266 NodeMCU 1.0

[earlephilhower]

Close the Serial Monitor and try again. There is no way for a plug in to do that for you per the Arduino folks.

[abaymar]

Indeed closing the Serial Monitor helps!