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Troubleshooting

For issues related to upgrading from GitHub Packages to public distribution, see the Upgrading Guide.

Streaming SSR request hangs indefinitely​

Symptom: Requests to streaming pages (or RSC payload endpoints) hang forever and never complete.

Cause: A compression middleware (Rack::Deflater, Rack::Brotli) is configured with an :if condition that calls body.each to check the response size. This destructively consumes streaming chunks from the SizedQueue, causing a deadlock.

Fix: See the "Compression Middleware Compatibility" section in the Streaming Server Rendering guide.

Node Renderer​

Connection refused to renderer​

Symptom: Errno::ECONNREFUSED or timeout errors when Rails tries to reach the node renderer.

Fixes:

  • Verify the renderer is running: curl http://localhost:3800/
  • Check that config.renderer_url in config/initializers/react_on_rails_pro.rb matches the renderer's actual port
  • On Heroku, ensure the renderer is started via Procfile.web (see Heroku deployment)

Workers crashing with memory leaks​

Symptom: Node renderer workers restart frequently or OOM.

Fixes:

  • Enable rolling restarts with allWorkersRestartInterval and delayBetweenIndividualWorkerRestarts — use high values to avoid all workers being down simultaneously
  • Profile memory using node --inspect (see Profiling guide)
  • Check for global state leaks and use config.ssr_pre_hook_js to clear them

Workers killed during streaming​

Symptom: Streaming pages fail mid-stream when worker restarts are enabled.

Fix: Set gracefulWorkerRestartTimeout to a high value or disable it, so workers are not killed while serving active streaming requests.

Fragment Caching​

Cache not being used​

Symptom: cached_react_component always evaluates the props block.

Fixes:

  • Verify Rails cache store is configured (not :null_store)
  • Check cache_key values — if they change every request, the cache will never hit
  • If your component depends on URL or locale, include those in the cache_key (see Caching docs)

Stale cached content after deploy​

Symptom: Components show old content after deploying new JavaScript bundles.

Fix: When prerender: true is set, the server bundle digest is automatically included in the cache key. If you're not prerendering, add your bundle hash to the cache key manually, or configure dependency_globs in react_on_rails_pro.rb to bust the cache on relevant file changes.

License​

License validation fails on startup​

Symptom: ReactOnRailsPro::LicenseError on Rails boot.

Fixes:

React Server Components​

RSC payload endpoint returns 500​

Symptom: The RSC payload route fails with an error.

Fixes:

  • Verify config.enable_rsc_support = true in config/initializers/react_on_rails_pro.rb
  • Check that rsc_bundle_js_file, react_client_manifest_file, and react_server_client_manifest_file are configured and the files exist
  • Ensure the RSC webpack config is building correctly (3 bundles: client, server, RSC)

Components not hydrating after streaming​

Symptom: Server-rendered HTML appears but React doesn't hydrate on the client.

Fixes:

  • Check that client-side JavaScript bundles are loaded (no 404s in browser console)
  • Verify immediate_hydration option — set to true for immediate hydration
  • Ensure client components have the 'use client' directive