go runtime_error ai_generated true

rpc error: code = Internal desc = grpc: error while marshaling: proto: Marshal called with nil

ID: go/grpc-internal-error-transport

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2025-02-14First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
grpc-go 1.60+ active — — —

Root Cause

The gRPC framework failed to marshal the response because a nil message was returned from the handler. The nil propagates to the codec.

generic

中文

gRPC 框架无法序列化响应，因为处理程序返回了 nil 消息。nil 传播到了编解码器。

Workarounds

  1. 95% success 
    Always return a non-nil response or an explicit error from handlers:
func (s *svc) Get(ctx context.Context, req *pb.Req) (*pb.Resp, error) {
    if req == nil {
        return nil, status.Error(codes.InvalidArgument, "nil request")
    }
    return &pb.Resp{...}, nil
}
  2. 90% success 
    Add a server interceptor to detect nil responses early:
func nilGuard(ctx context.Context, req, resp any, info *grpc.UnaryServerInfo, h grpc.UnaryHandler) (any, error) {
    r, err := h(ctx, req)
    if err == nil && r == nil { return nil, status.Error(codes.Internal, "handler returned nil") }
    return r, err
}

Dead Ends

Common approaches that don't work:

  1. 85% fail

    A nil response is a contract violation; a custom codec hides the bug and produces empty/garbage payloads.

  2. 75% fail

    Returning a non-nil but empty message masks the real logic error and clients receive semantically wrong data.