hashicorp/nomad · error

missing region for target RPC

Error message

missing region for target RPC

What it means

forward() requires every RPC to carry a target region via RPCInfo.RequestRegion(). An empty region means the request struct did not have its Region field set (or the RPCInfo implementation failed to provide it), so the handler cannot decide whether to serve locally or forward. This is an internal invariant violation rather than a user-facing condition.

Source

Thrown at nomad/rpc.go:588

		case pool.RpcNomad:
			go r.handleNomadConn(ctx, sub, rpcServer)
		case pool.RpcStreaming:
			go r.handleStreamingConn(sub)

		default:
			r.logger.Error("multiplex_v2 unrecognized first RPC byte", "byte", buf[0])
			return
		}
	}

}

// forward is used to forward to a remote region or to forward to the local leader
// Returns a bool of if forwarding was performed, as well as any error
func (r *rpcHandler) forward(method string, info structs.RPCInfo, args any, reply any) (bool, error) {
	region := info.RequestRegion()
	if region == "" {
		return true, fmt.Errorf("missing region for target RPC")
	}

	// Handle region forwarding
	if region != r.srv.config.Region {
		// Mark that we are forwarding the RPC
		info.SetForwarded()
		err := r.forwardRegion(region, method, args, reply)
		return true, err
	}

	// Check if we can allow a stale read
	if info.IsRead() && info.AllowStaleRead() {
		return false, nil
	}

	remoteServer, err := r.getLeaderForRPC()
	if err != nil {
		return true, err

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Set the Region field on the request struct before dispatching the RPC
2. Ensure the RPC type implements structs.RPCInfo (RequestRegion/SetRegion)
3. Check both server and client are on compatible Nomad versions
4. Fix custom/test code that builds requests without a region

Example fix

// before
req := &structs.JobListRequest{}
srv.RPC("Job.List", req, &reply)
// after
req := &structs.QueryOptions{Region: "us-east-1"}
srv.RPC("Job.List", req, &reply)

if req.RequestRegion() == "" {
    return fmt.Errorf("request Region must be set before RPC dispatch")
}

if _, err := srv.RPC(method, req, reply); err != nil && strings.Contains(err.Error(), "missing region") {
    return fmt.Errorf("caller bug: %s request had no Region set: %w", method, err)
}

When it happens

Trigger: An RPC request struct passed to forward() with an empty Region field — custom/forked RPC handlers, test code constructing bare request structs, or an RPC type missing SetRegion/RequestRegion wiring.

Common situations: Hand-built RPC calls in tests or tools against the Nomad internal API; new RPC endpoints added in forks that forget to set Region; version drift where a new endpoint is called against an older server lacking region handling.

Related errors

• missing NodeID
• cannot submit nil plan
• cannot submit plan without job info
• no servers
• missing NodeID

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/2d4c92899bb46d9f. Report an issue: GitHub.