If a celery task gets spawned soon after a DB write then it needs to query the master DB. Now that task exceptions show up in email, this out of sync scenario seems to happen occasionally. Here is an example: Task devhub.tasks.validator with id ba147472-2034-446f-bcdd-98dfa5b3c651 raised exception: "ObjectDoesNotExist('FileUpload matching query does not exist.',)" Task was called with args: ('a9491722be514f4c9c6791c7b1d9921f',) kwargs: {}. The contents of the full traceback was: Traceback (most recent call last): File "/data/www/addons-dev.allizom.org/zamboni/vendor/lib/python/celery/execute/trace.py", line 34, in trace return cls(states.SUCCESS, retval=fun(*args, **kwargs)) File "/data/www/addons-dev.allizom.org/zamboni/vendor/lib/python/celery/task/base.py", line 241, in __call__ return self.run(*args, **kwargs) File "/data/www/addons-dev.allizom.org/zamboni/vendor/lib/python/celery/app/__init__.py", line 141, in run return fun(*args, **kwargs) File "/data/www/addons-dev.allizom.org/zamboni/vendor/src/nuggets/celeryutils.py", line 35, in wrapped return fun(*args, **kw) File "/data/www/addons-dev.allizom.org/zamboni/apps/amo/decorators.py", line 112, in wrapper return f(*args, **kw) File "/data/www/addons-dev.allizom.org/zamboni/apps/amo/decorators.py", line 104, in wrapper return f(*args, **kw) File "/data/www/addons-dev.allizom.org/zamboni/apps/devhub/tasks.py", line 43, in validator upload = FileUpload.objects.get(pk=upload_id) File "/data/www/addons-dev.allizom.org/zamboni/vendor/src/django/django/db/models/manager.py", line 132, in get return self.get_query_set().get(*args, **kwargs) File "/data/www/addons-dev.allizom.org/zamboni/vendor/src/django/django/db/models/query.py", line 349, in get % self.model._meta.object_name) DoesNotExist: FileUpload matching query does not exist.

We actually get several of these a day, bumping up priority

I decided this wasn't worth the effort. Instead, we can use the existing @write decorator to pin tasks like this to the master DB. Fixed: https://github.com/mozilla/zamboni/commit/3edf647