Failed-error-during-websocket-handshake-connection-header-is-missing (2025)

: Force websocket transport: io('url', { transports: ['websocket'] }) .

Managed services often strip headers; ensure WebSocket support is enabled: : Enable Stickiness for polling fallbacks. Azure App Service : Toggle WebSockets on in configuration. 💻 Local Development Protocol : Ensure using ws:// or wss:// . : Force websocket transport: io('url'

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 : Force websocket transport: io('url'

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 . : Force websocket transport: io('url'