Today I got the information that Octoprint with the Python 2 no longer works in the long run and should be switched to the version Python 3. So I have a new image with OctoPrint 1.7.0 Python 3.7.3 OctoPi 0.18.0 and since then the communication to the printer Prusa MK3S does not work anymore. But with the Python 2 version it still worked.
What did you already try to solve it?
Read octoprint log and find this:
Traceback (most recent call last):
File "/home/pi/oprint/lib/python3.7/site-packages/serial/serialposix.py", line 144, in set_low_latency_mode
fcntl.ioctl(self.fd, termios.TIOCSSERIAL, buf)
OSError: [Errno 95] Operation not supported
The error you quoted also says it continued without and after there are some parts off a communication seen. Your printer then doesn't respond to an handshake attempt within 30s and OctoPrint gives up. I've seen this happen on my own MK3 occasionally, and usually when for whatever reason it takes ages to initialize right after reboot while scanning this files on the SD or is trying to connect to a non existent MMU.
To rule out the attempt to set low latency as the culprit, disable that under Settings > Serial > Connection.
