I've been using Octorprint to connect to my Crealty Ender Pro 3 for several months now. Recently I installed the PCU plugin, and the Octoprint stopped connecting to my printer.
I uninstalled the plugin, but that doesn't help. Here are my logs:
Changing monitoring state from "Detecting serial connection" to "Error: No more candidates to test, and no working port/baudrate combination detected."
Changing monitoring state from "Error: No more candidates to test, and no working port/baudrate combination detected." to "Offline (Error: No more candidates to test, and no working port/baudrate combination detected.)"
Connection closed, closing down monitor
Changing monitoring state from "Offline" to "Detecting serial connection"
Performing autodetection with 7 port/baudrate candidates: /dev/ttyACM0@115200, /dev/ttyACM0@250000, /dev/ttyACM0@230400, /dev/ttyACM0@57600, /dev/ttyACM0@38400, /dev/ttyACM0@19200, /dev/ttyACM0@9600
Trying port /dev/ttyACM0, baudrate 115200
Handshake attempt #1 with timeout 2.0s
Connected to: PackingSerial<id=0xae342d50, open=True>(port='/dev/ttyACM0', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=2.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 250000
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 230400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Unexpected error while reading serial port, please consult octoprint.log for details: SerialException: 'device reports readiness to read but returned no data (device disconnected or multiple access on port?)' @ comm.py:_readline:3831
Please see https://faq.octoprint.org/serialerror for possible reasons of this.
Changing monitoring state from "Detecting serial connection" to "Offline (Error: SerialException: 'device reports readiness to read but returned no data (device disconnected or multiple access on port?)' @ comm.py:_readline:3831)"
Connection closed, closing down monitor
Changing monitoring state from "Offline" to "Detecting serial connection"
Performing autodetection with 7 port/baudrate candidates: /dev/ttyACM0@115200, /dev/ttyACM0@250000, /dev/ttyACM0@230400, /dev/ttyACM0@57600, /dev/ttyACM0@38400, /dev/ttyACM0@19200, /dev/ttyACM0@9600
Trying port /dev/ttyACM0, baudrate 115200
Handshake attempt #1 with timeout 2.0s
Connected to: PackingSerial<id=0xae342d50, open=True>(port='/dev/ttyACM0', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=2.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 250000
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 230400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 57600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 38400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 19200
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 9600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Changing monitoring state from "Detecting serial connection" to "Error: No more candidates to test, and no working port/baudrate combination detected."
Changing monitoring state from "Error: No more candidates to test, and no working port/baudrate combination detected." to "Offline (Error: No more candidates to test, and no working port/baudrate combination detected.)"
Connection closed, closing down monitor
Changing monitoring state from "Offline" to "Detecting serial connection"
Performing autodetection with 7 port/baudrate candidates: /dev/ttyACM0@115200, /dev/ttyACM0@250000, /dev/ttyACM0@230400, /dev/ttyACM0@57600, /dev/ttyACM0@38400, /dev/ttyACM0@19200, /dev/ttyACM0@9600
Trying port /dev/ttyACM0, baudrate 115200
Handshake attempt #1 with timeout 2.0s
Connected to: PackingSerial<id=0xae342d50, open=True>(port='/dev/ttyACM0', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=2.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 250000
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 230400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 57600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 38400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 19200
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 9600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Changing monitoring state from "Detecting serial connection" to "Error: No more candidates to test, and no working port/baudrate combination detected."
Changing monitoring state from "Error: No more candidates to test, and no working port/baudrate combination detected." to "Offline (Error: No more candidates to test, and no working port/baudrate combination detected.)"
Connection closed, closing down monitor
Changing monitoring state from "Offline" to "Detecting serial connection"
Performing autodetection with 7 port/baudrate candidates: /dev/ttyACM0@115200, /dev/ttyACM0@250000, /dev/ttyACM0@230400, /dev/ttyACM0@57600, /dev/ttyACM0@38400, /dev/ttyACM0@19200, /dev/ttyACM0@9600
Trying port /dev/ttyACM0, baudrate 115200
Handshake attempt #1 with timeout 2.0s
Connected to: PackingSerial<id=0xae342d50, open=True>(port='/dev/ttyACM0', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=2.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 250000
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 230400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 57600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 38400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 19200
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 9600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Changing monitoring state from "Detecting serial connection" to "Error: No more candidates to test, and no working port/baudrate combination detected."
Changing monitoring state from "Error: No more candidates to test, and no working port/baudrate combination detected." to "Offline (Error: No more candidates to test, and no working port/baudrate combination detected.)"
Connection closed, closing down monitor
Changing monitoring state from "Offline" to "Detecting serial connection"
Performing autodetection with 7 port/baudrate candidates: /dev/ttyACM0@115200, /dev/ttyACM0@250000, /dev/ttyACM0@230400, /dev/ttyACM0@57600, /dev/ttyACM0@38400, /dev/ttyACM0@19200, /dev/ttyACM0@9600
Trying port /dev/ttyACM0, baudrate 115200
Handshake attempt #1 with timeout 2.0s
Connected to: PackingSerial<id=0xae342d50, open=True>(port='/dev/ttyACM0', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=2.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 250000
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 230400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 57600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 38400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 19200
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 9600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Changing monitoring state from "Detecting serial connection" to "Error: No more candidates to test, and no working port/baudrate combination detected."
Changing monitoring state from "Error: No more candidates to test, and no working port/baudrate combination detected." to "Offline (Error: No more candidates to test, and no working port/baudrate combination detected.)"
Connection closed, closing down monitor
Changing monitoring state from "Offline" to "Detecting serial connection"
Performing autodetection with 7 port/baudrate candidates: /dev/ttyACM0@115200, /dev/ttyACM0@250000, /dev/ttyACM0@230400, /dev/ttyACM0@57600, /dev/ttyACM0@38400, /dev/ttyACM0@19200, /dev/ttyACM0@9600
Trying port /dev/ttyACM0, baudrate 115200
Handshake attempt #1 with timeout 2.0s
Connected to: PackingSerial<id=0xae342d50, open=True>(port='/dev/ttyACM0', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=2.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 250000
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 230400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 57600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 38400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 19200
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 9600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s