You grab a snack and a tasty beverage, crash down onto your sofa, pick up the Apple TV remote, cue Netflix, hit play, and... get the horrible 'An error occurred loading this content. Try again later." message. You do, and... same error. Again, and again. You snack turns soggy, your beverage goes flat, and Netflix still gives you nothing but errors and frustration. That was me. Tonight. Until I remembered that a restart fixes just about everything!
Or, if you're using the actual Apple TV hardware remote (rather than the iOS Remote app), simply hold down the Menu and Play/Pause button until it restarts.
Once your Apple TV reboots to the Home screen, go back into Netflix, choose your show, and you should be good to go. Yes, the solution is sub-optimal. Having to reboot, especially if it happens frequently, is super annoying. It would be better if, after the error occurs, Apple TV would automatically kill and cycle the app/connection. But, this works for now. (If only the lack of Netflix content outside the U.S. were so easily fixed!)
If you get the content loading error, especially if you get it frequently, let me know how often, and let me know if this fix — or a better one! — works for you!