It’s not just you: Google Play Music is restricting access in all browsers except Chrome
If you subscribe to Google Play Music All Access, and routinely access the streaming music service in Firefox, Safari, Internet Explorer, or basically any browser that’s not Chrome, you might have been experiencing some issues lately. Starting around June 9, users have been complaining that the web app simply isn’t functioning correctly, preventing subscribers from streaming most music.
Most peculiar is that it does not seem to affect music that users have uploaded themselves; instead, it’s only music that users stream from the vast All Access cloud library. Users have reported that the issue happens using both the Flash and the HTML5 music players, and the only workaround is to access Google Play Music All Access in Chrome, or through the official app for Android or iOS.
My theory is that something is messed up with the DMCA copyright protection on these music files, but in any case, Google does seem interested in working out a fix and getting people access once again. Stay tuned, keep refreshing the web app, and hopefully you’ll have access again soon.[Google via Android Police]