Dremio Websockets are being blocked

1

Your Internet connection may be offline or WebSockets to Dremio are being blocked.

I have on premise deployment with dremio and now i am facing this issue on and off, 1 month ago all going well and now the issue comeback again, no upgrade in dremio software recently.

anyone have the same problems ?

Thankyou

2

@jowinatha Is it a single node that serves as both Coordinator and Executor?

hat error — “Your Internet connection may be offline or WebSockets to Dremio are being blocked” — means that the Dremio UI can’t connect to the Dremio server using WebSockets, which it relies on for communication. Here’s how to diagnose and fix it:

:magnifying_glass_tilted_left: 1. Check Your Internet Connection

  • Make sure you’re connected to the internet and can access other sites.

  • If you’re on a VPN or corporate network, try temporarily disconnecting or switching to another network to see if the issue persists.

:brick: 2. Verify WebSocket Access

Dremio’s web UI requires WebSocket connections (port 9047 by default) to stay open.
If these are blocked, you’ll see that error.

To check:

  1. Open your browser’s developer console (F12 → “Network” tab).

  2. Filter for “WS” requests.

  3. You should see a connection to something like:

    wss://<your-dremio-host>:9047/apiv2/socket

    If it fails, something (like a firewall or proxy) is blocking WebSocket traffic.

Fixes:

  • Allow WebSocket traffic on port 9047 (or your configured UI port).

  • Ensure your proxy or firewall allows wss:// connections to the Dremio endpoint.

  • If you’re using Nginx, Apache, or a load balancer in front of Dremio, make sure WebSocket proxying is enabled:

    proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";

:desktop_computer: 3. Clear Browser Cache / Try Another Browser

Sometimes cached UI resources cause connection errors.

  • Clear your cache and reload (Ctrl + F5).

  • Try using Chrome or Firefox in Incognito/Private mode.

:gear: 4. Check the Dremio Server Status

If the backend service is down or restarting, you’ll see this too.

  • Confirm that Dremio is running:

    systemctl status dremio

    or

    ps aux | grep Dremio

  • Check logs under $DREMIO_HOME/logs/server.log for any errors.

:technologist: 5. For Dremio Cloud Users

If you’re on Dremio Cloud, this can also happen if:

  • Your browser extensions (like ad blockers) interfere with WebSockets.

  • Your corporate proxy filters WebSocket traffic to *.dremio.cloud.

Try disabling extensions or whitelisting Dremio Cloud domains.