In Qt 5.5.1 whilst using the serial port, if the connection is open and then the USB device is removed from the mac, an error is emitted (ResourceError), in which an attempt is made to close the port if PortOpen is true, when this is called another error is emitted (ResourceError) which then does the same thing until the stack limit is reached and the application crashes.

In Linux and Windows, this issue does not occur. I have not tried but looking at the code for the sample terminal application looks like it too will cause the issue: http://doc.qt.io/qt-5/qtserialport-terminal-example.html