: Force websocket transport: io('url', { transports: ['websocket'] }) .
The error occurs when a client tries to establish a WebSocket connection, but a network intermediary (like a reverse proxy or load balancer) strips out the required HTTP headers needed to upgrade the connection from standard HTTP to WebSockets .
Which or server framework are you currently using to host this application?
Here are the most common solutions based on your infrastructure: 🚀 Nginx Configuration Fix
RewriteCond %{HTTP:Upgrade} websocket [NC] RewriteCond %{HTTP:Connection} upgrade [NC] RewriteRule /(.*) ws://localhost:8080/$1 [P,L] Use code with caution. Copied to clipboard ☁️ Cloud Providers & Load Balancers
