Issue With Appengine Deferred Tasks, Execution Throws Unknown Error

I have task deferred in appengine python its a simple call with all task_info strings, list of strings. It works well for any no of tasks. deferred.defer(fetch_serv

Solution 1:

This problem is specific to the GAE python scaffold provided by Google. There's a whitelist of methods that are allowed to be pickled.

If you add your fetch_service method to the _PICKLE_CLASS_WHITELIST in base/api_fixers.py list, it will work.

Solution 2:

The PermanentTaskFailure exception indicates that a task failed, and will never succeed.

This typically means some invalid condition is encountered when the GAE infra attempts to schedule the task.

The None.fetch_service string in the error message points to an invalid reference: None doesn't have a fetch_service attribute.

This could indicate the task execution is attempted in a module which doesn't have access to the fetch_service object. I'd check the imports in the module displaying the error.