Course Builder error 500 issue when adding new unit

[christos vassilopoulos]

Hi. I have an app in appspot using the Course Builder. App worked fine until a few days ago where when I try to add a new Unit I get: 500 Internal Server Error  The server has either erred or is incapable of performing the requested operation.

I checked the log files and saw that the error that repeats is 

AttributeError: 'NoneType' object has no attribute 'lesson_id'

get (/base/data/home/apps/e~sev-exports/20170426t200457.400835856987044385/controllers/lessons.py:139)

RAW shows:

Traceback (most recent call last):
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1535, in __call__
    rv = self.handle_exception(request, response, e)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1529, in __call__
    rv = self.router.dispatch(request, response)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1278, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1102, in __call__
    return handler.dispatch()
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 572, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 570, in dispatch
    return method(*args, **kwargs)
  File "/base/data/home/apps/e~sev-exports/20170426t200457.400835856987044385/controllers/sites.py", line 868, in get
    handler.get()
  File "/base/data/home/apps/e~sev-exports/20170426t200457.400835856987044385/controllers/lessons.py", line 139, in get
    self.template_value['lesson_id'] = lesson.lesson_id
AttributeError: 'NoneType' object has no attribute 'lesson_id'

Any ideas/solutions?

Thanks.

[Jun (Cloud Platform Support)]

Hi Christos,

Google Groups is meant for general product discussions and not for technical support.

It is recommended you open an issue at the Issue Tracker report with more information such as your project-ID, app.yaml/appengine-web.xml config files, and the exact timestamp of when this issue occurred so that our support can better assist you, thanks!

- Jun