Traceback (most recent call last):


 "/opt/OpenWPM/demo.py", line 37, in <module>

manager = TaskManager.TaskManager(manager_params, browser_params)


 "/opt/OpenWPM/automation/TaskManager.py", line 144, in __init__

self._launch_browsers()


 "/opt/OpenWPM/automation/TaskManager.py", line 182, in _launch_browsers

self.close()


 "/opt/OpenWPM/automation/TaskManager.py", line 565, in close

self._shutdown_manager()


 "/opt/OpenWPM/automation/TaskManager.py", line 260, in _shutdown_manager

browser.shutdown_browser(during_init)


 "/opt/OpenWPM/automation/BrowserManager.py", line 358, in shutdown_browser

self.close_browser_manager()


 "/opt/OpenWPM/automation/BrowserManager.py", line 266, in close_browser_manager

self.kill_browser_manager()


 "/opt/OpenWPM/automation/BrowserManager.py", line 312, in kill_browser_manager

self.crawl_id, self.browser_manager.pid,
AttributeError: 'NoneType' object has no attribute 'pid'

Traceback (most recent call last):


 "~/venv/lib/python2.7/site-packages/flask/app.py", line 1982, in wsgi_app

response = self.full_dispatch_request()


 "~/venv/lib/python2.7/site-packages/flask/app.py", line 1614, in full_dispatch_request

rv = self.handle_user_exception(e)


 "~/venv/lib/python2.7/site-packages/flask/app.py", line 1517, in handle_user_exception

reraise(exc_type, exc_value, tb)


 "~/venv/lib/python2.7/site-packages/flask/app.py", line 1612, in full_dispatch_request

rv = self.dispatch_request()


 "~/venv/lib/python2.7/site-packages/flask/app.py", line 1598, in dispatch_request

return self.view_functions[rule.endpoint](**req.view_args)


 "~/app/api/users.py", line 45, in create_user

response = jsonify(user.to_dict())


 "~/app/models.py", line 171, in to_dict

'last_seen': self.last_seen.isoformat() + 'Z',
AttributeError: 'NoneType' object has no attribute 'isoformat'
