Could not open port COM4 (ESP8266)

[PeteKnight]

You should probably read this, rather than picking pins at random:

ESP8266 GPIO pins info, restrictions and features

hi blynkers! the esp8266 mcu is widely used in iot projects. however, most gpio pins on this mcu have special / multiple functionality and are not safe to use in all circumstances. these “features” are still not well documented and not explained in a friendly manner for newbies. i see lots of cases when the “issues” are simply caused by not knowing which pins to use in which case. [esp8266 pin features] here is a basic table for startup. i’ve collected the info from various sources on the i…

Pete.