celery/celery · error · NotImplementedError

Must implement the set method.

Error message

Must implement the set method.

What it means

Error "Must implement the set method." thrown in celery/celery.

Source

Thrown at celery/backends/base.py:1011

            self.group_keyprefix = f"{global_keyprefix}{self.group_keyprefix}"
            self.chord_keyprefix = f"{global_keyprefix}{self.chord_keyprefix}"

    def _encode_prefixes(self):
        self.task_keyprefix = self.key_t(self.task_keyprefix)
        self.group_keyprefix = self.key_t(self.group_keyprefix)
        self.chord_keyprefix = self.key_t(self.chord_keyprefix)

    def get(self, key):
        raise NotImplementedError('Must implement the get method.')

    def mget(self, keys):
        raise NotImplementedError('Does not support get_many')

    def _set_with_state(self, key, value, state):
        return self.set(key, value)

    def set(self, key, value):
        raise NotImplementedError('Must implement the set method.')

    def delete(self, key):
        raise NotImplementedError('Must implement the delete method')

    def incr(self, key):
        raise NotImplementedError('Does not implement incr')

    def expire(self, key, value):
        pass

    def get_key_for_task(self, task_id, key=''):
        """Get the cache key for a task by id."""
        if not task_id:
            raise ValueError(f'task_id must not be empty. Got {task_id} instead.')
        return self._get_key_for(self.task_keyprefix, task_id, key)

    def get_key_for_group(self, group_id, key=''):
        """Get the cache key for a group by id."""

View on GitHub (pinned to 571efe8120)

When it happens

Trigger: Thrown at celery/backends/base.py:1011 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of celery/celery@571efe8120 (2026-08-04). Data as JSON: /data/errors/7acdf1d88cd8908c.json. Report an issue: GitHub.