Same issue on 2different devices. Both my wife's iPhone and my Android get stuck on "Connecting...". The issue appeared like a day or two ago, before that everything was working fine. Now none of the devices can't connect.
Yes, I tried rebooting both phones, the router, the Chromecast, resetting the Chromecast to factory settings and even reinstalling the Spotify app. Didn't help.
All other Cast-enabled apps (i.e. Soundcloud, TuneIn) both on the iPhone and the Android ARE CONNECTING AND CASTING seamlessly. So it's obviously the Spotify who screwed something up.
I met the same problem yesterday and today when I tried to play anyone of the 3 daily mixes. On any Chromecast Audio (I have two), it was working for a few seconds, then was stopping with a never ending message "connection...". Then I tried to play any other song, not a daily mix. It worked with no problem on both of my devices. I came back to the daily mixes, it carried on working nicely. I really have no explanation, I just report it as I lived it...
Making sure i am on the same wifi network as i have set up on the chromecast audio. Sometimes i find i just have to relaunch the spotify app on my phone after changing to the correct wifi network.
Also, Note apple users on mac: if you want to connect to chromecast audio wirelessly on MacOS then you need to be in Spotify's web player to have this festure work, and NOT in the desktop app. The desktop app doesnt yet have the chromecast support.
Since doing either of these fixes i haven't run into any other problems and my chromecast audio work perfectly with spotify. I hope this helps
Same issue here today. Google Play Music has no issues, Spotify times out when trying to connect to the Chromecast Audio. The sound when a device connects to the Chromecast Audio is played, but in Spotify the connecting animation keeps resting until it gives up and plays the music on my phone.
Having big troubles using chromecast from the spotify app for a few weeks now. Spotify seemed to have troubles with chromecast eversince, but now it doesn't work at all.
I tried everything mentioned here and elsewhere on the web, factory resets, new installations, removed all device , cleared caches, etc. pp. If it semms to work, it's only for a day, then the problems are back. All my 4 different devices have the same problems with Spotify, other apps work like a charm.
This is really annoying and I will not renew my Premium after january because this is the way I listen to music at home. Sadly I will leave spotify. They do not seem to care about Chromecast users.