# rpc error: code = Unimplemented desc = unknown method SayHello

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

## Root Cause

The server does not implement the requested RPC method, possibly due to outdated proto generation.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 1.56.x | active | — | — |
| 1.57.x | active | — | — |

## Workarounds

1. **** (95% success)
   ```
   protoc --go_out=. --go-grpc_out=. *.proto; go build -o server server.go
   ```
2. **** (90% success)
   ```
   if err := pb.RegisterGreeterServer(s, &server{}); err != nil { log.Fatal(err) }
   ```
3. **** (85% success)
   ```
   Ensure method name matches exactly: client.SayHello(ctx, req)
   ```

## Dead Ends

- **Trying other methods that also don't exist.** — All methods may be unimplemented. (80% fail)
- **Using nil response from failed call.** — Nil pointer dereference. (90% fail)
- **Assuming the method was removed.** — May still be needed. (60% fail)