Failed-error-during-websocket-handshake-connection-header-is-missing Apr 2026

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

If you are using Nginx as a reverse proxy, you must explicitly tell it to forward the Upgrade and Connection headers. By default, Nginx does not do this. Add or update your location block in your nginx.conf file: Add or update your location block in your nginx

Ensure mod_proxy and mod_proxy_wstunnel are enabled. Use a RewriteRule in your VirtualHost to pass WebSocket traffic: 💻 Local Development Protocol : Ensure using ws://

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:// . Nginx does not do this.

Which or server framework are you currently using to host this application?

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 .

Here are the most common solutions based on your infrastructure: 🚀 Nginx Configuration Fix