Replit
ui
WebSocket Connection Failed on Replit
WebSocket connections fail with network errors or close immediately. Real-time features like chat or notifications don't work.
WebSocket configuration and deployment differences between local and Replit cause issues.
Error Messages You Might See
WebSocket connection to 'ws://...' failed
Could not upgrade to WebSocket
Error: Could not find message broker relay
Common Causes
- WebSocket endpoint not exposed or misconfigured
- CORS not allowing WebSocket upgrade requests
- Proxy/load balancer not forwarding WebSocket protocol
- Client using wrong WebSocket URL (ws instead of wss, or localhost)
- StompBroker not configured for Spring WebSocket
How to Fix It
For Spring WebSocket, use WebSocketConfigurer and registerStompEndpoints(). Enable CORS with allowed origins. Client should use 'wss://' (secure WebSocket) on Replit. Verify endpoint path matches client connection URL. Check browser console for actual error message and upgrade handshake details.
Real developers can help you.
Vlad Temian
15+ years shipping production infrastructure for startups. Former CTO at qed.builders (acquired by The Sandbox).
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Daniel Vázquez
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Sage Fulcher
Hey I'm Sage! Im a Boston area software engineer who grew up in South Florida. Ive worked at a ton of cool places like a telehealth kidney care startup that took part in a billion dollar merger (Cricket health/Interwell health), a boutique design agency where I got to work on a ton of exciting startups including a photography education app, a collegiate Esports league and more (Philosophie), a data analytics as a service startup in Cambridge (MA) as well as at Phillips and MIT Lincoln Lab where I designed and developed novel network security visualizations and analytics. I've been writing code and furiously devoted to using computers to make people’s lives easier for about 17 years. My degree is in making computers make pretty lights and sounds. Outside of work I love hip hop, the Celtics, professional wrestling, magic the gathering, photography, drumming, and guitars (both making and playing them)
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Get HelpFrequently Asked Questions
Should I use ws:// or wss:// on Replit?
Use wss:// (secure) on production. Client auto-detects based on page protocol
How do I configure Spring WebSocket?
Implement WebSocketConfigurer, register endpoint with registerStompEndpoints()