# rpc error: code = Unimplemented desc = unknown service helloworld.Greeter

- **ID:** `go/grpc-unimplemented-service`
- **Domain:** go
- **Category:** network_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Client is calling a gRPC service that the server has not registered. The server may not have the correct .proto compiled, or the service registration is missing.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 1.x | active | — | — |

## Workarounds

1. **** (95% success)
   ```
   In server main: pb.RegisterGreeterServer(s, &server{})
   ```
2. **** (90% success)
   ```
   protoc --go_out=. --go-grpc_out=. helloworld.proto
   ```

## Dead Ends

- **** — The server binary still contains old generated code, so the service is still unavailable. (80% fail)
- **** — This will only produce a different Unimplemented error, not fix the root cause. (90% fail)