protoc3 grpc (go) code generation problem

The issue is in my view is straightforward:

Your protoc-gen-go-grpc is v1.6.1 generated code that references grpc.SupportPackageIsVersion9 and grpc.StaticMethod(), but your google.golang.org/grpc dependency in go.mod is an older version that doesn't have these symbols yet, so the incompatibility issue

The protoc compiler itself is indeed neutral here — the incompatibility is between the code generator plugin version and the grpc-go runtime library in your project.

The Fix

You need your google.golang.org/grpc module dependency to be v1.64.0 or later (that's when SupportPackageIsVersion9 and StaticMethod were introduced).

Run this from your project root: go get google.golang.org/grpc@latest go mod tidy

That should resolve both errors without touching the generated code.

Why This Happened

When you ran go install ...@latest, you got the newest generator plugins, which emit code targeting the newest grpc-go runtime. But your project's go.mod still pinned an older google.golang.org/grpc version. There's no single compatibility matrix published, but the general rule is: if you use @latest for the generators, also use @latest (or at least a recent version) for the runtime dependency.

Alternative Approach

If for some reason you need to stay on an older grpc-go runtime, you can install an older generator instead:

bash

go install google.golang.org/grpc/cmd/[email protected]

This would generate code compatible with older grpc-go versions (using SupportPackageIsVersion7). However upgrading the runtime is the cleaner path.