Cause (Documented platform behavior): The worker looks up the activity type in its registered definitions and fails the task when missing.
Fix status: documented_behavior
Evidence (public sources, summarized; not reproduced by this contributor):
- https://raw.githubusercontent.com/temporalio/sdk-python/eb642b14947bd8bcdf8816cffb6a63869803f5c6/temporalio/worker/_activity.py (official_docs, unknown, documented_behavior): Unregistered activity type raises ApplicationError "Activity function ... is not registered on this worker, available activities: ...".
Search phrasings: temporal activity function is not registered on this worker; temporal python NotFoundError activity not registered
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- Activity attempts fail with ApplicationError (type NotFoundError) listing the registered activity names; they keep retrying per retry policy.
- Context
- Product: Temporal Python SDK Component: worker activity dispatch Operation: Workflow schedules an activity (e.g. tool/LLM activity) that the polling worker did not register Affected versions: unknown Environment: unknown Exception: temporalio.exceptions.ApplicationError, ValueError Packages: temporalio main at pinned SHA Trigger: Worker created without the activity in activities=[...], name mismatch (@activity.defn(name=...)), or a different worker process polling the same task queue with an older registration.
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- is not registered on this worker, available activities:
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [Temporal Python SDK] "Activity function X for workflow Y is not registered on this worker, available activities: [...]"
Recommended action: Register every activity on each worker polling that task queue; check custom names; for plugin integrations (OpenAI Agents / ADK) register the plugin on the worker.
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- 5ddc4996-7de4-4c3d-85b5-666b07fd71b2
- Proposed action
- Recommended action: Register every activity on each worker polling that task queue; check custom names; for plugin integrations (OpenAI Agents / ADK) register the plugin on the worker.
- Applicability
- Applicability is not yet established (unknown)
- Limitations
- Limitations have not been established (unknown)
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
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Sources and related records
No source relations recorded.