Octopi Keeps Disconnecting

What is the problem?
Octoprint keeps disconnecting from the printer. I've never had a problem until today. "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:2823"

What did you already try to solve it?
Checked for updates, none.
Used a new USB cable.
Replace the power supply.

Logs (octoprint.log, serial.log or output on terminal tab at a minimum, browser error console if UI issue ... no logs, no support!)

system:
|  Action Command Prompt Support (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/action_command_prompt
|  Announcement Plugin (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/announcements
|  Anonymous Usage Tracking (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/tracking
|  Application Keys Plugin (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/appkeys
|  AstroPrint (1.5.3) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_astroprint
|  Automatic Shutdown (0.1.4) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_automaticshutdown
|  Backup & Restore (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/backup
|  Bed Visualizer (0.1.13) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_bedlevelvisualizer
|  Cancel Objects (0.4.1) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_cancelobject
|  Core Wizard (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/corewizard
|  Dashboard (1.11.4) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_dashboard
|  Discovery (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/discovery
|  DisplayLayerProgress Plugin (1.20.0) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_DisplayLayerProgress
|  Error Tracking (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/errortracking
|  Exclude Region (0.2.0) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_excluderegion
|  GcodeEditor (0.2.8) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_GcodeEditor
|  Logging (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/logging
|  Login UI (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/loginui
|  Navbar Temperature Plugin (0.13) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_navbartemp
|  Pi Support Plugin (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/pi_support
|  Plugin Manager (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/pluginmanager
|  Printer Safety Check (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/printer_safety_check
|  PrintTimeGenius Plugin (2.2.1) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_PrintTimeGenius
|  Remove /dev/ttyS* ports (0.1.0) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_remove_ttys_ports
|  Simple Emergency Stop (1.0.1) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_simpleemergencystop
|  Software Update (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/softwareupdate
|  Themeify (1.2.2) = /home/pi/oprint/local/lib/python2.7/site-packages/octoprint_themeify
|  Virtual Printer (bundled) = /home/pi/oprint/lib/python2.7/site-packages/octoprint/plugins/virtual_printer
Prefix legend: ! = disabled, # = blacklisted, * = incompatible
2020-04-21 03:19:37,194 - octoprint.environment - INFO - Detected environment is Python 2.7.16 under Linux (linux2). Details:
|  hardware:
|      cores: 4
|      freq: 1500.0
|      ram: 1979613184
|  os:
|      id: linux
|      platform: linux2
|  plugins:
|      pi_support:
|          model: Raspberry Pi 4 Model B Rev 1.1
|          octopi_version: 0.17.0
|  python:
|      pip: 20.0.2
|      version: 2.7.16
|      virtualenv: /home/pi/oprint
2020-04-21 03:19:37,204 - octoprint.server - INFO - Reset webasset folder /home/pi/.octoprint/generated/webassets...
2020-04-21 03:19:37,224 - octoprint.server - INFO - Reset webasset folder /home/pi/.octoprint/generated/.webassets-cache...
2020-04-21 03:19:37,876 - octoprint.server - INFO - Shutting down intermediary server...
2020-04-21 03:19:37,927 - octoprint.server - INFO - Intermediary server shut down
2020-04-21 03:19:37,929 - octoprint.events - INFO - Processing startup event, this is our first event
2020-04-21 03:19:37,931 - octoprint.events - INFO - Adding 1 events to queue that were held back before startup event
2020-04-21 03:19:37,934 - octoprint.server - INFO - Autoconnect on startup is configured, trying to connect to the printer...
2020-04-21 03:19:37,934 - octoprint.filemanager - INFO - Adding backlog items from all storage types to analysis queue...
2020-04-21 03:19:37,973 - octoprint.plugins.pluginmanager - INFO - Loaded plugin repository data from disk, was still valid
2020-04-21 03:19:38,302 - octoprint.filemanager - INFO - Added 0 items from storage type "local" to analysis queue
2020-04-21 03:19:38,608 - octoprint.plugins.pluginmanager - INFO - Loaded notice data from disk, was still valid
2020-04-21 03:19:38,645 - octoprint.server - INFO - Trying to connect to configured serial port None
2020-04-21 03:19:38,807 - octoprint.util.comm - INFO - Changing monitoring state from "Offline" to "Detecting serial port"
2020-04-21 03:19:38,926 - octoprint.server.util.watchdog - INFO - Running initial scan on watched folder...
2020-04-21 03:19:38,990 - octoprint.server.util.watchdog - INFO - ... initial scan done.
2020-04-21 03:19:39,008 - octoprint.plugins.discovery - INFO - Registered 'OctoPrint instance on octopi' for _http._tcp
2020-04-21 03:19:39,018 - octoprint.util.comm - INFO - Changing monitoring state from "Detecting serial port" to "Opening serial port"
2020-04-21 03:19:39,023 - octoprint.util.comm - INFO - Changing monitoring state from "Opening serial port" to "Connecting"
2020-04-21 03:19:39,022 - octoprint.plugins.discovery - INFO - Registered 'OctoPrint instance on octopi' for _octoprint._tcp
2020-04-21 03:19:39,034 - octoprint.util.comm - INFO - M110 detected, setting current line number to 0
2020-04-21 03:19:39,043 - octoprint.util.comm - INFO - M110 detected, setting current line number to 0
2020-04-21 03:19:39,047 - octoprint.plugins.discovery - INFO - Registered OctoPrint instance on octopi for SSDP
2020-04-21 03:19:39,056 - octoprint.util.comm - INFO - Changing monitoring state from "Connecting" to "Operational"
2020-04-21 03:19:39,145 - octoprint.util.comm - INFO - M110 detected, setting current line number to 0
2020-04-21 03:19:39,161 - octoprint.util.comm - INFO - Printer reports firmware name "Marlin 2.0.5.3 (GitHub)"
2020-04-21 03:19:39,186 - octoprint.util.comm - INFO - Firmware states that it supports temperature autoreporting
2020-04-21 03:19:39,242 - octoprint.server - INFO - Listening on http://127.0.0.1:5000
2020-04-21 03:19:39,326 - octoprint.plugins.pluginmanager - INFO - Loaded plugin repository data from disk, was still valid
2020-04-21 03:19:39,371 - octoprint.server.util.sockjs - INFO - New connection from client: 2002:2f9c:9f0c:0:308a:ea7:25e1:c38b
2020-04-21 03:19:39,633 - octoprint.util.pip - INFO - Using "/home/pi/oprint/bin/python2 -m pip" as command to invoke pip
2020-04-21 03:19:39,791 - octoprint.util.pip - INFO - Using "/home/pi/oprint/bin/python2 -m pip" as command to invoke pip
2020-04-21 03:19:39,816 - octoprint.server.util.flask - INFO - Passively logging in user caseysimonmft from ::ffff:192.168.1.31
2020-04-21 03:19:39,829 - octoprint.access.users - INFO - Logged in user: caseysimonmft
2020-04-21 03:19:39,877 - octoprint.server.util.sockjs - INFO - User caseysimonmft logged in on the socket from client 2002:2f9c:9f0c:0:308a:ea7:25e1:c38b
2020-04-21 03:19:40,123 - octoprint.plugins.tracking - INFO - Sent tracking event printer_connected, payload: {u'printer_baudrate': 115200, u'printer_port': None, 'firmware_name': u'Marlin 2.0.5.3 (GitHub)'}
2020-04-21 03:19:40,164 - octoprint.util.pip - INFO - Using "/home/pi/oprint/bin/python2 -m pip" as command to invoke pip
2020-04-21 03:19:40,477 - octoprint.plugins.pluginmanager - INFO - Loaded notice data from disk, was still valid
2020-04-21 03:19:41,736 - octoprint.util.pip - INFO - pip installs to /home/pi/oprint/lib/python2.7/site-packages/ (writable -> yes), --user flag needed -> no, virtual env -> yes
2020-04-21 03:19:41,737 - octoprint.util.pip - INFO - ==> pip ok -> yes
2020-04-21 03:19:41,741 - octoprint.util.pip - INFO - pip installs to /home/pi/oprint/lib/python2.7/site-packages (writable -> yes), --user flag needed -> no, virtual env -> yes
2020-04-21 03:19:41,745 - octoprint.util.pip - INFO - ==> pip ok -> yes
2020-04-21 03:19:41,826 - octoprint.plugins.softwareupdate - INFO - Saved version cache to disk
2020-04-21 03:19:41,835 - octoprint.plugins.astroprint - INFO - No print files yaml: /home/pi/.octoprint/data/astroprint/print_files.yaml
2020-04-21 03:19:41,896 - octoprint.plugins.astroprint - INFO - No stored AstroPrint user
2020-04-21 03:19:41,898 - octoprint.plugins.bedlevelvisualizer - INFO - OctoPrint-BedLevelVisualizer loaded!
2020-04-21 03:19:41,899 - octoprint.plugins.dashboard - INFO - Dashboard started
2020-04-21 03:19:41,904 - octoprint.plugins.navbartemp - INFO - Broadcom detected
2020-04-21 03:19:41,905 - octoprint.plugins.themeify - INFO - Themeify initialized.
2020-04-21 03:19:42,104 - octoprint.server.preemptive_cache - INFO - Preemptively caching / (ui _default) for {'query_string': 'l10n=en', 'path': '/', 'base_url': 'http://octopi.local/'}
2020-04-21 03:19:42,587 - octoprint.plugins.tracking - INFO - Sent tracking event ping, payload: {'octoprint_uptime': 7}
2020-04-21 03:19:43,304 - octoprint.plugins.tracking - INFO - Sent tracking event startup, payload: {'python': '2.7.16', 'ram': 1979613184, u'octopi_version': u'0.17.0', 'version': u'1.4.0', 'pip': '20.0.2', 'cores': 4, 'freq': 1500.0, u'pi_model': u'Raspberry Pi 4 Model B Rev 1.1', 'os': 'linux'}
2020-04-21 03:19:44,159 - octoprint.plugins.tracking - INFO - Sent tracking event pong, payload: {'plugins': u'displaylayerprogress:1.20.0,gcodeeditor:0.2.8,cancelobject:0.4.1,astroprint:1.5.3,remove_ttys_ports:0.1.0,themeify:1.2.2,bedlevelvisualizer:0.1.13,automaticshutdown:0.1.4,simpleemergencystop:1.0.1,navbartemp:0.13,excluderegion:0.2.0,dashboard:1.11.4,printtimegenius:2.2.1'}
2020-04-21 03:19:48,680 - octoprint.server.preemptive_cache - INFO - ... done in 6.58s
2020-04-21 03:19:51,917 - octoprint.server.util.flask - INFO - Passively logging in user caseysimonmft from ::ffff:192.168.1.31
2020-04-21 03:19:51,919 - octoprint.access.users - INFO - Logged in user: caseysimonmft
2020-04-21 03:19:52,023 - octoprint.server.util.sockjs - INFO - Client connection closed: 2002:2f9c:9f0c:0:308a:ea7:25e1:c38b
2020-04-21 03:19:53,917 - octoprint.server.util.sockjs - INFO - New connection from client: 2002:2f9c:9f0c:0:308a:ea7:25e1:c38b
2020-04-21 03:19:54,035 - octoprint.server.util.flask - INFO - Passively logging in user caseysimonmft from ::ffff:192.168.1.31
2020-04-21 03:19:54,036 - octoprint.access.users - INFO - Logged in user: caseysimonmft
2020-04-21 03:19:55,549 - octoprint.server.util.sockjs - INFO - User caseysimonmft logged in on the socket from client 2002:2f9c:9f0c:0:308a:ea7:25e1:c38b
2020-04-21 03:21:14,138 - octoprint.util.comm - ERROR - Unexpected error while reading from serial port
Traceback (most recent call last):
  File "/home/pi/oprint/local/lib/python2.7/site-packages/octoprint/util/comm.py", line 2823, in _readline
    ret = self._serial.readline()
  File "/home/pi/oprint/local/lib/python2.7/site-packages/octoprint/util/comm.py", line 4968, in readline
    c = self.read(1)
  File "/home/pi/oprint/local/lib/python2.7/site-packages/serial/serialposix.py", line 501, in read
    'device reports readiness to read but returned no data '
SerialException: device reports readiness to read but returned no data (device disconnected or multiple access on port?)
2020-04-21 03:21:14,241 - octoprint.util.comm - ERROR - Please see https://faq.octoprint.org/serialerror for possible reasons of this.
2020-04-21 03:21:14,285 - octoprint.util.comm - INFO - Changing monitoring state from "Operational" to "Offline (Error: SerialException: 'device reports readiness to read but returned no data (device disconnected or multiple access on port?)' @ comm.py:_readline:2823)"
2020-04-21 03:21:29,867 - octoprint.util.comm - INFO - Changing monitoring state from "Offline" to "Detecting serial port"
2020-04-21 03:21:29,904 - octoprint.util.comm - INFO - Changing monitoring state from "Detecting serial port" to "Opening serial port"
2020-04-21 03:21:29,907 - octoprint.util.comm - INFO - Changing monitoring state from "Opening serial port" to "Connecting"
2020-04-21 03:21:29,939 - octoprint.util.comm - INFO - M110 detected, setting current line number to 0
2020-04-21 03:21:44,858 - octoprint.util.comm - ERROR - Unexpected error while reading from serial port
Traceback (most recent call last):
  File "/home/pi/oprint/local/lib/python2.7/site-packages/octoprint/util/comm.py", line 2823, in _readline
    ret = self._serial.readline()
  File "/home/pi/oprint/local/lib/python2.7/site-packages/octoprint/util/comm.py", line 4968, in readline
    c = self.read(1)
  File "/home/pi/oprint/local/lib/python2.7/site-packages/serial/serialposix.py", line 501, in read
    'device reports readiness to read but returned no data '
SerialException: device reports readiness to read but returned no data (device disconnected or multiple access on port?)
2020-04-21 03:21:44,926 - octoprint.util.comm - ERROR - Please see https://faq.octoprint.org/serialerror for possible reasons of this.
2020-04-21 03:21:44,956 - octoprint.util.comm - INFO - Changing monitoring state from "Connecting" to "Offline (Error: SerialException: 'device reports readiness to read but returned no data (device disconnected or multiple access on port?)' @ comm.py:_readline:2823)"

Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, browser, operating system, ... as much data as possible)
octopi_version: 0.17.0
Ender 3 pro using BTT SKR 1.2

  • The serial cable needs internal metallic shielding or a ferrite core, be as short as possible, not have any additional inline adapters, fit snugly at both ends
  • You need a 5V @ 2.5A power adapter (not a charger) and it needs to fit snugly at both ends and it shouldn't sink power over to the printer's controller board
  • The power as measured at the wall needs to be what it's supposed to be (consider plugging all this into a UPS)
  • No USB-based LEDs
  • If you've done all this, try Safe Mode
  • If you've done all this, try dropping the baud rate by half

Thanks, I’ve done most of the above. I’ll try safe mode.