This article covers the issue that produces a 426 error code in the console log.
A newly created agent user is attempting to log into chat portal but is seeing the 426 error in the console logs.
In chrome if you open the developer tools (right click > inspect element. Or press F12 on a windows machine).
The error will look something like this:
If you encounter this error you will need to contact your network administrator who can run a test on https://www.websocket.org/echo.html
We often use this to test websocket connectivity, just click 'Connect' to the default location (wss://echo.websocket.org) and see if the websocket connects. Check you can send messages and your test is complete.
We have found the error is generated from the websocket connection being blocked by local firewalls, you will need to ask your network administrator to allow this connection in order for users to connect and chat with agents.