googleapis/mcp-toolbox · error

toolbox does not support streaming in streamable HTTP transp

Error message

toolbox does not support streaming in streamable HTTP transport

What it means

Error "toolbox does not support streaming in streamable HTTP transport" thrown in googleapis/mcp-toolbox.

Source

Thrown at internal/server/mcp.go:493

	for {
		select {
		// Ensure that only a single responses are written at once
		case event := <-session.eventQueue:
			fmt.Fprint(w, event)
			s.logger.DebugContext(ctx, fmt.Sprintf("sending event: %s", event))
			flusher.Flush()
			// channel for client disconnection
		case <-clientClose:
			close(session.done)
			s.logger.DebugContext(ctx, "client disconnected")
			return
		}
	}
}

// methodNotAllowed handles all mcp messages.
func methodNotAllowed(s *Server, w http.ResponseWriter, r *http.Request) {
	err := fmt.Errorf("toolbox does not support streaming in streamable HTTP transport")
	s.logger.DebugContext(r.Context(), err.Error())
	_ = render.Render(w, r, newErrResponse(err, http.StatusMethodNotAllowed))
}

// httpHandler handles all mcp messages.
func httpHandler(s *Server, w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")

	ctx := r.Context()
	ctx = util.WithLogger(ctx, s.logger)
	ctx = util.WithUserAgent(ctx, s.version)
	ctx = util.WithSQLCommenterEnabled(ctx, s.sqlCommenterEnabled)

	queryParams := r.URL.Query()
	urlParams := make(map[string]string)
	for k, v := range queryParams {
		if k == "sessionId" {
			continue

View on GitHub (pinned to 8cc6e09de2)

When it happens

Trigger: Thrown at internal/server/mcp.go:493 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/00ff2e93c34dfad2. Report an issue: GitHub.