Multiple Arduino IDE instances and serial monitor issues


Well-known member
Looks like the "port busy" on Windows & MacOS we often hear reports, and maybe also strange serial monitor issues on Linux might be related to having 2 Arduino IDE instances open.

With Arduino IDE 1.8.19, there may be some ways the IDE is still running in the background (including a serial monitor), even though all windows appear to be gone. Spent a several hours investigating today, then accidentally crashed my machine while forcibly killing the lingering processes.

Mainly leaving this here as a note to future me... cause I'm exhausted on this issue right now. Was hoping to finally address this in 1.59, but might have to wait.