Problem restarting: haven't been able to update plugins for a while

After running a "succesful" plugin upgrade (MQTT in this case but it applies to all), the servers doesn't restart and if I go back to the page, I can see it's not ben updated. Stopping the server and restarting it doesn't solve the issue

Server was started this way: OctoPrint ~/OctoPrint/venv/bin/octoprint serve

What did you already try to solve it?

I have ugpraded pip. That didn't help.

I have run this again:

source venv/bin/activate
pip install pip --upgrade
pip install https://get.octoprint.org/latest

which got me to pip: 19.0.3 and reverted to Octoprint 1.3.9 but that didn't help and I can't update to 1.3.10 anymore (same as updating a plugin).

Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, octoprint.log, serial.log or output on terminal tab, ...)

OctoPrint 1.3.10

{'python': '2.7.13', 'ram': 918188032, 'version': u'1.3.10', 'pip': '18.0', 'cores': 4, 'freq': 1200.0, 'pi_model': 'Raspberry Pi 3 Model B Rev 1.2', 'os': 'linux'}

2019-02-22 21:02:19,975 - octoprint.util.pip - INFO - Using "/home/pi/OctoPrint/venv/bin/python2 -m pip" as command to invoke pip
2019-02-22 21:02:31,930 - octoprint.util.pip - INFO - pip installs to /home/pi/OctoPrint/venv/lib/python2.7/site-packages/ (writable -> yes), --user flag needed -> no, virtual env -> yes
2019-02-22 21:02:31,932 - octoprint.util.pip - INFO - ==> pip ok -> yes
2019-02-22 21:02:54,053 - octoprint.plugins.softwareupdate - INFO - Update of mqtt to 0.8.1 successful!
2019-02-22 21:02:55,009 - octoprint.plugins.tracking - INFO - Sent tracking event update_successful, payload: {'to_version': '0.8.1', 'from_version': '0.8.0', 'target': u'mqtt'}
2019-02-22 21:02:56,726 - octoprint.plugins.softwareupdate - INFO - Saved version cache to disk
2019-02-22 21:02:56,730 - octoprint.plugins.softwareupdate - INFO - Restarting...
Exception in thread Thread-64:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 801, in __bootstrap_inner
self.run()
File "/usr/lib/python2.7/threading.py", line 754, in run
self.__target(*self.__args, **self.__kwargs)
File "/home/pi/OctoPrint/venv/lib/python2.7/site-packages/octoprint/plugins/softwareupdate/init.py", line 919, in _update_worker
self._perform_restart(restart_command)
File "/home/pi/OctoPrint/venv/lib/python2.7/site-packages/octoprint/plugins/softwareupdate/init.py", line 1024, in _perform_restart
util.execute(restart_command, evaluate_returncode=False, do_async=True)
File "/home/pi/OctoPrint/venv/lib/python2.7/site-packages/octoprint/plugins/softwareupdate/util.py", line 29, in execute
return p.returncode, p.stdout.text, p.stderr.text
File "/home/pi/OctoPrint/venv/local/lib/python2.7/site-packages/sarge/init.py", line 1081, in returncode
return self.commands[-1].process.returncode
AttributeError: 'NoneType' object has no attribute 'returncode'

That's probably why it doesn't work now, if I'm guessing correctly. I think it's time for a start-over.

More