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FAQ: WebSocket/STOMP does not work (Safari downloads iframe.html)

Symptoms

  • 403/400 on GET /stomp/** in the UI.
  • In backend logs: DefaultHandshakeHandler: "Handshake failed due to invalid Upgrade header: null".
  • SockJS falls back and downloads /stomp/iframe.html (in Safari).

Cause

Ordinary NGINX (VM) is used without a WebSocket proxy (no Upgrade/Connection: upgrade, HTTP/1.1 is not enabled, and there is no separate location for /stomp/**).

Solution

Add a separate block for /stomp/**:


# Upstream: Cabinee backend (legacy compose service name: unibpm)
location /stomp/ {
    proxy_pass http://unibpm/;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_read_timeout 86400;
}