There has definitely been a major spike of the reports of this "avrdude: ser_open(): can't set com-state for ..." error. Fortunately some of the users who were affected in the early days of the spike identified the correlation between the error and the CH340 driver and shared their findings. That information was essential in developing the procedures I shared here because I am not able to reproduce the fault on my own system when uploading to CH340-based boards even though I have the same problematic driver version installed.
Other than @txa, all the other users have reported that the problem is fixed by one of the two procedures so I think I have been able to at least mitigate the impact.
As for upload errors with other causes, a bug in Arduino IDE is causing an increase in the "Access is denied" errors, but that has been in effect for at least 7 months now so it should not be driving a more recent increase in reports. And surprisingly the number of reports has been relatively low (I guess because the FTDI FT232R-based boards are not so common these days).
