Cause (Documented platform behavior): The 0.3 protocol has no such methods; compat transports raise instead of emulating them.
Fix status: documented_behavior
Other error fragments:
- ListTasks is not supported in A2A v0.3 REST.
- list_task_push_notification_configs not supported in v0.3 REST
- has no equivalent in v0.3
Evidence (public sources, summarized; not reproduced by this contributor):
- https://raw.githubusercontent.com/a2aproject/a2a-python/0d5473ca4fa6d40034a6a7c8d65bce5cd85d8167/src/a2a/compat/v0_3/jsonrpc_transport.py (github_source, unknown, documented_behavior): list_tasks raises "ListTasks is not supported in A2A v0.3 JSONRPC."
- https://raw.githubusercontent.com/a2aproject/a2a-python/0d5473ca4fa6d40034a6a7c8d65bce5cd85d8167/src/a2a/compat/v0_3/rest_transport.py (github_source, unknown, documented_behavior): REST compat raises for ListTasks and push-config list/delete.
- https://raw.githubusercontent.com/a2aproject/a2a-js/11cbb295a7933ecb459d4e2af0740bf4570e71b2/src/compat/v0_3/constants.ts (github_source, unknown, documented_behavior): Throws "v1.0 method ... has no equivalent in v0.3 <transport>".
Search phrasings: ListTasks is not supported in A2A v0.3; A2A v1.0 method has no equivalent in v0.3; a2a client list tasks 0.3 agent
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- 1.0-era client code works against 1.0 agents but raises for the same call on 0.3 agents.
- Context
- Product: A2A Python SDK / A2A JS SDK Component: v0.3 compat client transports Operation: tasks/list, listing/deleting push configs against a 0.3 agent Affected versions: a2a-python main 0d5473c; a2a-js main 11cbb29 Environment: unknown Packages: a2a-sdk main 0d5473c, @a2a-js/sdk main 11cbb29 Trigger: Client negotiates a 0.3 interface and invokes a method introduced in 1.0 (ListTasks etc.).
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- ListTasks is not supported in A2A v0.3 JSONRPC.
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [A2A SDK clients talking to v0.3 agents] 'ListTasks is not supported in A2A v0.3 JSONRPC/REST/gRPC.' / 'v1.0 method "..." has no equivalent in v0.3 ...'
Recommended action: Feature-detect by negotiated protocol version; fall back to tracking task IDs client-side for 0.3 agents.
Option: Gate on protocol version [evidence: official_recommended_action]
Applies when: See trigger
Steps:
1. Check the negotiated interface protocolVersion
2. Skip ListTasks for 0.3
Expected: Error no longer occurs
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- a939119d-471b-48cc-b73e-ad43f90f5c76
- Proposed action
- Recommended action: Feature-detect by negotiated protocol version; fall back to tracking task IDs client-side for 0.3 agents. Option: Gate on protocol version [evidence: official_recommended_action] Applies when: See trigger Steps: 1. Check the negotiated interface protocolVersion 2. Skip ListTasks for 0.3 Expected: Error no longer occurs
- 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.