a2a_mcp report errors

[gyliu513]

What happened?

(a2a_mcp) a2a_mcp % uv run src/a2a_mcp/agents/ --agent-card agent_cards/orchestrator_agent.json --port 10101
Uninstalled 1 package in 4ms
Installed 1 package in 3ms
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/src/a2a_mcp/agents/__main__.py", line 13, in <module>
    from a2a.server.apps import A2AStarletteApplication
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/.venv/lib/python3.13/site-packages/a2a/server/apps/__init__.py", line 3, in <module>
    from a2a.server.apps.jsonrpc import (
    ...<4 lines>...
    )
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/.venv/lib/python3.13/site-packages/a2a/server/apps/jsonrpc/__init__.py", line 3, in <module>
    from a2a.server.apps.jsonrpc.fastapi_app import A2AFastAPIApplication
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/.venv/lib/python3.13/site-packages/a2a/server/apps/jsonrpc/fastapi_app.py", line 7, in <module>
    from a2a.server.apps.jsonrpc.jsonrpc_app import (
    ...<2 lines>...
    )
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/.venv/lib/python3.13/site-packages/a2a/server/apps/jsonrpc/jsonrpc_app.py", line 21, in <module>
    from a2a.server.request_handlers.jsonrpc_handler import JSONRPCHandler
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/.venv/lib/python3.13/site-packages/a2a/server/request_handlers/__init__.py", line 6, in <module>
    from a2a.server.request_handlers.grpc_handler import GrpcHandler
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/.venv/lib/python3.13/site-packages/a2a/server/request_handlers/grpc_handler.py", line 10, in <module>
    import a2a.grpc.a2a_pb2_grpc as a2a_grpc
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/.venv/lib/python3.13/site-packages/a2a/grpc/a2a_pb2_grpc.py", line 5, in <module>
    from . import a2a_pb2 as a2a__pb2
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/.venv/lib/python3.13/site-packages/a2a/grpc/a2a_pb2.py", line 12, in <module>
    _runtime_version.ValidateProtobufRuntimeVersion(
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
        _runtime_version.Domain.PUBLIC,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<4 lines>...
        'a2a.proto'
        ^^^^^^^^^^^
    )
    ^
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/.venv/lib/python3.13/site-packages/google/protobuf/runtime_version.py", line 106, in ValidateProtobufRuntimeVersion
    _ReportVersionError(
    ~~~~~~~~~~~~~~~~~~~^
        'Detected mismatched Protobuf Gencode/Runtime major versions when'
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        f' loading {location}: gencode {gen_version} runtime {version}.'
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        f' Same major version is required. {error_prompt}'
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/gyliu513/go/src/github.com/google-a2a/a2a-samples/samples/python/agents/a2a_mcp/.venv/lib/python3.13/site-packages/google/protobuf/runtime_version.py", line 50, in _ReportVersionError
    raise VersionError(msg)
google.protobuf.runtime_version.VersionError: Detected mismatched Protobuf Gencode/Runtime major versions when loading a2a.proto: gencode 6.31.1 runtime 5.29.5. Same major version is required. See Protobuf version guarantees at https://protobuf.dev/support/cross-version-runtime-guarantee.

Relevant log output

Code of Conduct

• I agree to follow this project's Code of Conduct

[rgstephens]

The project has a dependency of protobuf 5.29.5 but the a2a.proto file which is part of a2a-sdk was generated with 6.31.1.

Workaround:

samples/python/agents/a2a_mcp
uv venv
source venv/bin/activate
uv sync
uv pip install protobuf==6.31.1
python src/a2a_mcp/agents --agent-card agent_cards/air_ticketing_agent.json --port 10103

[rajeshvelicheti]

a2a_mcp might be using a lower version of the SDK. I will update this to latest in the dependency.

The protobuf version issue is resolved in the latest version of the SDK.

As a workaround, you could update pyproject.toml on a2a_mcp project to use the latest SDK.

[rajeshvelicheti]

#167

a2aproject/a2a-python#224

Should solve the issue.

[gyliu513]

Thanks @rajeshvelicheti , it works. I actually used same fix when I workaround this :)