Mac(Catalina10.15.7) can't open device "/dev/cu.usbmodem14101": Resource busy

[Uttchy]

ここで質問していいのかわからないけれど、互換品購入によるトラブル。
ボード情報は受け取れるが「マイコンボードに書き込む」を実行すると以下のメッセージが出て使えません。

Arduino：1.8.16 (Mac OS X), ボード："Arduino Uno"

     Using Port                    : /dev/cu.usbmodem14101
     Using Programmer              : arduino
     Overriding Baud Rate          : 115200

avrdude: ser_open(): can't open device "/dev/cu.usbmodem14101": Resource busy

avrdude done. Thank you.

Problem uploading to board. See https://support.arduino.cc/hc/en-us/sections/360003198300 for suggestions.

お助けください。

[J-M-L]

Do you have a terminal window already opened and using that port?

[Uttchy]

Yes, I have selected this from the terminal window.

/dev/cu.usbmodem14101

Thank you.

[Uttchy]

I bought a regular ARDUINO UNO R3, but I get the same error.
This error seems to be the problem.

can't open device "/dev/cu.usbmodem14201": Resource busy

If you have any solution, please let me know.

[Uttchy]

After writing many times, I found that it was rarely successful.
I plugged in the USB cable while holding down the reset button and pressed reset for 10 seconds. I read the writing, so I tried it, but I feel that the success rate will increase a little.
Sometimes I get an error even after writing 100 times, and sometimes I succeed in the third time.
If the writing is successful, disconnect the USB and use an external power supply to operate.