TypeError 'NoneType' object is not subscriptable

[mthompson313]

I am seeing an issue where asgiref/local.py is throwing a TypeError 'NoneType' object is not subscriptable

this is being thrown from:

def __getattr__(self, key):
        storage_object = self._data.get({})
        try:
            return storage_object[key]
        except KeyError:
            raise AttributeError(f"{self!r} object has no attribute {key!r}")

[andrewgodwin]

Could I get a full traceback please plus the code that's calling it?

[mthompson313]

Full Stack Trace:

TypeError: 'NoneType' object does not support item assignment
  File "django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
  File "ddtrace/contrib/trace_utils.py", line 334, in wrapper
    return func(mod, pin, wrapped, instance, args, kwargs)
  File "ddtrace/contrib/django/patch.py", line 302, in wrapped
    return func(*args, **kwargs)
  File "axes/middleware.py", line 37, in __call__
    response = self.get_response(request)
  File "asgiref/local.py", line 124, in __setattr__
    setattr(storage, key, value)
  File "asgiref/local.py", line 28, in __setattr__
    storage_object[key] = value
TypeError: 'NoneType' object is not subscriptable
  File "django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
  File "ddtrace/contrib/trace_utils.py", line 334, in wrapper
    return func(mod, pin, wrapped, instance, args, kwargs)
  File "ddtrace/contrib/django/patch.py", line 302, in wrapped
    return func(*args, **kwargs)
  File "discovery_service/middleware.py", line 119, in __call__
    response = self.get_response(request)
  File "django/core/handlers/exception.py", line 57, in inner
    response = response_for_exception(request, exc)
  File "django/core/handlers/exception.py", line 141, in response_for_exception
    request, get_resolver(get_urlconf()), sys.exc_info()
  File "django/urls/base.py", line 145, in get_urlconf
    return getattr(_urlconfs, "value", default)
  File "asgiref/local.py", line 118, in __getattr__
    return getattr(storage, key)
  File "asgiref/local.py", line 19, in __getattr__
    return storage_object[key]
TypeError: 'NoneType' object is not subscriptable
  File "django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
  File "ddtrace/contrib/trace_utils.py", line 334, in wrapper
    return func(mod, pin, wrapped, instance, args, kwargs)
  File "ddtrace/contrib/django/patch.py", line 302, in wrapped
    return func(*args, **kwargs)
  File "discovery_service/middleware.py", line 16, in __call__
    response = self.get_response(request)
  File "django/core/handlers/exception.py", line 57, in inner
    response = response_for_exception(request, exc)
  File "django/core/handlers/exception.py", line 141, in response_for_exception
    request, get_resolver(get_urlconf()), sys.exc_info()
  File "django/urls/base.py", line 145, in get_urlconf
    return getattr(_urlconfs, "value", default)
  File "asgiref/local.py", line 118, in __getattr__
    return getattr(storage, key)
  File "asgiref/local.py", line 19, in __getattr__
    return storage_object[key]
TypeError: 'NoneType' object is not subscriptable
  File "django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
  File "ddtrace/contrib/trace_utils.py", line 334, in wrapper
    return func(mod, pin, wrapped, instance, args, kwargs)
  File "ddtrace/contrib/django/patch.py", line 302, in wrapped
    return func(*args, **kwargs)
  File "django/utils/deprecation.py", line 134, in __call__
    response = response or self.get_response(request)
  File "django/core/handlers/exception.py", line 57, in inner
    response = response_for_exception(request, exc)
  File "django/core/handlers/exception.py", line 141, in response_for_exception
    request, get_resolver(get_urlconf()), sys.exc_info()
  File "django/urls/base.py", line 145, in get_urlconf
    return getattr(_urlconfs, "value", default)
  File "asgiref/local.py", line 118, in __getattr__
    return getattr(storage, key)
  File "asgiref/local.py", line 19, in __getattr__
    return storage_object[key]
TypeError: 'NoneType' object is not subscriptable
  File "django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
  File "ddtrace/contrib/trace_utils.py", line 334, in wrapper
    return func(mod, pin, wrapped, instance, args, kwargs)
  File "ddtrace/contrib/django/patch.py", line 302, in wrapped
    return func(*args, **kwargs)
  File "django/utils/deprecation.py", line 134, in __call__
    response = response or self.get_response(request)
  File "django/core/handlers/exception.py", line 57, in inner
    response = response_for_exception(request, exc)
  File "django/core/handlers/exception.py", line 141, in response_for_exception
    request, get_resolver(get_urlconf()), sys.exc_info()
  File "django/urls/base.py", line 145, in get_urlconf
    return getattr(_urlconfs, "value", default)
  File "asgiref/local.py", line 118, in __getattr__
    return getattr(storage, key)
  File "asgiref/local.py", line 19, in __getattr__
    return storage_object[key]

[mthompson313]

@andrewgodwin the code calling it I am having hard time finding as this came from a sentry alert on a production box. but the farthest down line given is:

 else:
        @wraps(get_response)
        def inner(request):
            try:
                response = get_response(request)
            except Exception as exc:
                response = response_for_exception(request, exc)
            return response
        return inner

from django/core/handlers/exception.py

[andrewgodwin]

Yeah, we're not going to be able to confirm if this is a true bug or not unless it's possible to get a reproduceable test case that doesn't have ddtrace in there mucking things up.

[mthompson313]

I believe the most recent commit to local.py should fix this issue