After updating to OctoPrint 1.4.1, I am no longer able to connect to my Prusa MK3S. I am running Octoprint on OctoPi 0.17.1 with Python 2.7.16 on a RasPi 4 2GB. The Pi boots and I am able to connect using via the web interface, but when I click on Connect (Serial Port Auto, Baud Rate Auto), I get the error: could not write to serial port. I am connecting via USB plugged into one of the USB2 ports on the Pi.
If I manually choose the serial port as Dev/tty/ACM0, the Prusa reboots, then OctoPrint gives the error: No more candidates to test, and no working port/baudrate combination detected.
If I manually choose the serial port as Dev/tty/AMA0, the Prusa does not reboot, and I get the OctoPrint error: Could not write to port.
There have been zero physical changes between a working connection under 1.4.0 an hour ago, and the update to 1.4.1
Log attached octoprint-3.log (115.6 KB)