Printer stopped after around 30 hours

Hello,
i just did my first big print with Octoprint and my Ender 3, after around 30 hours of printing the printer stopped at around 75%. I checked the log file and it seems that the printer somehow lost the connection to my Ender 3. Any ideas how this happened and how to prevent this error? (I printed about 50 parts, this never happened before)

Here is the Octoprint.log file:

...
2019-03-07 23:28:58,943 - octoprint.server.heartbeat - INFO - Server heartbeat <3
2019-03-07 23:28:59,481 - octoprint.plugins.tracking - INFO - Sent tracking event ping, payload: {}
2019-03-07 23:29:01,868 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:29:31,915 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:30:01,962 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:30:32,008 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:31:02,055 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:31:32,101 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:32:02,148 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:32:32,195 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:32:38,478 - tornado.access - WARNING - 409 GET /api/printer/bed (::ffff:192.168.178.201) 10.18ms
2019-03-07 23:32:38,492 - tornado.access - WARNING - 409 GET /api/printer/tool?limit=20&history=true (::ffff:192.168.178.201) 10.37ms
2019-03-07 23:32:38,502 - octoprint.server.util.sockjs - INFO - New connection from client: ::ffff:192.168.178.201
2019-03-07 23:32:38,802 - tornado.access - WARNING - 409 GET /api/printer/bed (::ffff:192.168.178.201) 10.06ms
2019-03-07 23:32:38,817 - tornado.access - WARNING - 409 GET /api/printer/tool?limit=20&history=true (::ffff:192.168.178.201) 10.26ms
2019-03-07 23:32:39,081 - tornado.access - WARNING - 409 GET /api/printer/tool?limit=20&history=true (::ffff:192.168.178.201) 9.90ms
2019-03-07 23:32:39,096 - tornado.access - WARNING - 409 GET /api/printer/bed (::ffff:192.168.178.201) 10.40ms
2019-03-07 23:32:40,644 - octoprint.util.comm - INFO - Changing monitoring state from "Offline" to "Detecting serial port"
2019-03-07 23:32:40,669 - tornado.access - WARNING - 409 GET /api/printer/tool?limit=20&history=true (::ffff:192.168.178.201) 13.95ms
2019-03-07 23:32:40,685 - tornado.access - WARNING - 409 GET /api/printer/bed (::ffff:192.168.178.201) 12.46ms
2019-03-07 23:32:40,833 - octoprint.util.comm - INFO - Changing monitoring state from "Detecting serial port" to "Opening serial port"
2019-03-07 23:32:40,841 - octoprint.util.comm - INFO - Changing monitoring state from "Opening serial port" to "Detecting baudrate"
2019-03-07 23:32:41,856 - octoprint.util.comm - INFO - M110 detected, setting current line number to 0
2019-03-07 23:32:42,122 - octoprint.util.comm - INFO - Changing monitoring state from "Detecting baudrate" to "Operational"
2019-03-07 23:32:42,155 - octoprint.util.comm - INFO - M110 detected, setting current line number to 0
2019-03-07 23:32:42,910 - octoprint.server.util.sockjs - INFO - Client connection closed: ::ffff:192.168.178.201
2019-03-07 23:32:42,911 - octoprint.server.util.sockjs - WARNING - Could not send message to client ::ffff:192.168.178.201: 'NoneType' object has no attribute 'send_pack'
2019-03-07 23:32:42,919 - octoprint.server.util.sockjs - WARNING - Could not send message to client ::ffff:192.168.178.201: 'NoneType' object has no attribute 'send_pack'
2019-03-07 23:32:42,922 - octoprint.server.util.sockjs - WARNING - Could not send message to client ::ffff:192.168.178.201: 'NoneType' object has no attribute 'send_pack'
2019-03-07 23:32:42,924 - octoprint.server.util.sockjs - WARNING - Could not send message to client ::ffff:192.168.178.201: 'NoneType' object has no attribute 'send_pack'
2019-03-07 23:32:43,638 - octoprint.util.comm - INFO - Printer reports firmware name "Marlin TH3D U1.R2.7"
2019-03-07 23:32:43,824 - octoprint.plugins.tracking - INFO - Sent tracking event printer_connected, payload: {u'printer_baudrate': 0, u'printer_port': None, 'firmware_name': 'Marlin TH3D U1.R2.7'}
2019-03-07 23:32:50,605 - octoprint.server.util.sockjs - INFO - New connection from client: ::ffff:192.168.178.201
2019-03-07 23:33:00,848 - octoprint.server.util.sockjs - INFO - Client connection closed: ::ffff:192.168.178.201
2019-03-07 23:33:02,242 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:33:02,366 - octoprint.server.util.sockjs - INFO - New connection from client: ::ffff:192.168.178.201
2019-03-07 23:33:11,547 - octoprint.server.util.sockjs - INFO - Client connection closed: ::ffff:192.168.178.201
2019-03-07 23:33:12,845 - octoprint.server.util.sockjs - INFO - New connection from client: ::ffff:192.168.178.201
2019-03-07 23:33:15,591 - octoprint.server.util.sockjs - INFO - Client connection closed: ::ffff:192.168.178.201
2019-03-07 23:33:32,356 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:33:33,839 - octoprint.server.util.sockjs - INFO - New connection from client: ::ffff:192.168.178.201
2019-03-07 23:33:34,031 - octoprint.server.util.flask - INFO - Passively logging in user Jan from ::ffff:192.168.178.201
2019-03-07 23:33:35,655 - octoprint.server.util.sockjs - INFO - User Jan logged in on the socket from client ::ffff:192.168.178.201
2019-03-07 23:34:02,405 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:34:32,457 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:35:02,507 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:35:32,557 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature
2019-03-07 23:36:02,606 - octoprint.plugins.navbartemp - INFO - Checking SoC internal temperature