gRPC sync ServerInterceptor._find_name broken with grpcio >= 1.76

[yeung108]

Problem

The sync ServerInterceptor._find_name in sentry_sdk/integrations/grpc/server.py is broken with grpcio >= 1.76.

Root Cause

grpcio 1.76 introduced registered method handlers (add_registered_method_handlers) which resolve RPC methods at the C-core level by tag. For these registered methods:

• context._rpc_event.call_details.method → empty (the Cython-compiled cygrpc._ServicerContext doesn't populate this field)
• handler_call_details.method → always populated (set by grpcio's _find_method_handler)

The current sync implementation reads from the empty field:

@staticmethod
def _find_name(context: "ServicerContext") -> str:
    return context._rpc_event.call_details.method.decode()

Impact

When _find_name returns an empty string, no Sentry transaction is created, meaning:

• No traces
• No spans
• No trace ID in logs

The exception from accessing the empty method is caught by upstream interceptors, so requests still succeed — but tracing is silently broken.

The Fix Already Exists in Async Version

The async version (sentry_sdk/integrations/grpc/aio/server.py) already uses the correct approach:

async def intercept_service(self, continuation, handler_call_details):
    self._handler_call_details = handler_call_details  # Stores it
    # ...

def _find_name(self, context: "ServicerContext") -> str:
    return self._handler_call_details.method  # Reads from stored details

Suggested Fix

Align the sync version with the async implementation:

1. Store handler_call_details in intercept_service
2. Change _find_name from @staticmethod to instance method
3. Read from self._handler_call_details.method

Environment

• sentry-sdk version: 2.52.0 (and earlier)
• grpcio version: >= 1.76.0
• Python version: 3.12

Related

• The async ServerInterceptor already works correctly
• This is not the same as issue gRPC (AIO) missing None check for when RPC method not implemented #3108 (which is about missing None checks for unimplemented methods)

[linear]

PY-2094