Unable to watch any streams on Steam

I have been trying to watch my friend playing a game and every time I try it says "Updating Steam..." and after 30 seconds it fails to show the stream and says "Failed to apply a Steam update that is required to watch this broadcast.

Please ensure your client is connected to Steam and try again."

I am connected to Steam, I am connected to the community. I'm using the beta Steam (which is completely up-to-date) and this is the first time I've had this problem. What do?

Unable to watch any streams on Steam