Movie won't play, or not in HD, on an external display or TV

Why it happens

Films from the TV app and many streaming sites are copy-protected with something called HDCP. Every part between your Mac and the screen, including the cable, dock, adapter and the display itself, has to support it. If one part doesn't, the picture goes black or the film drops to lower quality.

How to fix it

1. On a Mac laptop, play the film on the built-in screen. If it plays there, the problem is the connection to the other display. On a desktop Mac, try another monitor or TV if you have one.

2. Connect the display with a single cable straight from your Mac, with no hub or dock in between, if your Mac has a matching port.

3. If you need an adapter or dock, check its specs say it supports HDCP. Many cheap adapters and older docks don't.

4. Quit the app with Command-Q, or close the browser tab, then open it again and play the film.

Still not fixed?

1. If your Mac went to sleep while the film was playing, quit the app and open it again. Protected playback often needs a fresh start after sleep.

2. Going through a hub? Plug the monitor straight into a Thunderbolt or USB-C port. Then open Displays settings, hold Option and click Detect Displays.

   Displays›Detect Displays

3. If the screen stays black for everything, not just films, unplug and replug the cable and restart your Mac. That's a different problem from HDCP.

4. Older TVs, projectors and capture devices may not support HDCP at all. Check the manual, or try another screen.

5. If films won't play on any external screen even with a direct cable, but play fine on the built-in one, contact Apple Support. If only one display fails, its maker or a repair shop can check its ports.