Usually this error occurs because the radio station you are trying to listen to is running on an unencrypted port (not 443). This is quite common and it's not technically necessary for radio stations to be encrypted but nowadays web browsers like Chrome and Firefox have started disallowing...
We've started showing a "No Web Player" message (Shoutcast v1) for radio stations which won't play in the browser. These stations can still be played but only via the ".pls" and .m3u" links we display above the message.
The latest update (v55) being rolled out for Google Chrome unfortunately...