I also have not determined the cause of this error. I have been collecting some references with the idea of eventually doing a survey to see whether I can find a good explanation or a pattern that will allow me to identify the cause, but I haven't found the time for it. Here is the list of links in case you want to take a look:
- Cant set COM-state - Web Editor - Arduino Forum
- An error occurred while uploading the sketch avrdude: ser_open(): can't set com- - Avrdude, stk500, Bootloader issues - Arduino Forum
- ser_open(): can't set com-state for "\\.\COM5" temporary - IDE 1.x - Arduino Forum
- Upload error - IDE 1.x - Arduino Forum
- avrdude: ser_open(): can't set com-state for "\\.\COM3" - Avrdude, stk500, Bootloader issues - Arduino Forum
- Executing Command: exit status 1 ?!? - Programming Questions - Arduino Forum
- Upload errỏ ! - IDE 1.x - Arduino Forum
- cant upload a program - IDE 1.x - Arduino Forum
- Error uploading code to arduino Mega 2560 board. - #3 by arduino12_5 - IDE 1.x - Arduino Forum
- Weird error when uploading sketch
- https://forum.arduino.cc/t/a-small-trouble/853394
That is completely unrelated. The "Error: 2 UNKNOWN: exit status 1" is a very generic error message that only means something went wrong. There are a near infinite number of possible causes of this error message, so it shouldn't be used for correlation purposes. The more meaningful error message from the linked bug report is "undefined reference to `main'", whereas the one here is "can't set com-state". The one in the bug report is coming from the avr-gcc compiler, while this one is coming from the AVRDUDE uploader tool.