# WebSocket connection to 'wss://x' failed

**Code:** `WebSocket failed` · **Category:** JavaScript · **Seen on:** JavaScript

The browser couldn’t open (or keep) a WebSocket connection.

## Meaning

Proxies that don’t forward the Upgrade header, ws:// from an HTTPS page, wrong paths, and load balancer idle timeouts are typical.

## Common causes

- Reverse proxy not forwarding Upgrade/Connection headers
- ws:// used on an HTTPS page (must be wss://)
- Wrong URL/path or server down
- Idle timeout closing the connection

## Quick fix

1. Configure proxy upgrade headers
2. Use wss:// on HTTPS pages
3. Send ping/heartbeats
4. Check the server logs for the handshake

## Detailed fix by platform

### Nginx

1. 

```nginx
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
```


## How to diagnose

1. **Handshake** — Status of the upgrade request (101 expected)?
2. **Proxy** — Upgrade headers forwarded?

---
Source: [WhatIsMyError](https://whatismyerror.com/errors/javascript/websocket-connection-failed)