When you create a card in Photos, you need to choose a theme for the card. If you choose a newly added theme before it's fully downloaded, you might find that Photos becomes unresponsive.
You can avoid this by allowing new theme previews to download completely before you use them. Follow these steps:
- If Photos isn't responding, press Command-Option-Escape. The Force Quit Applications window appears. Select Photos, click Force Quit, and then click Force Quit again to confirm.
- Install any software updates that are available for your Mac.
- Restart your Mac.
- Open Photos.
- Select the photos you want to use in your card, click the plus icon at the top of the Photos window, and choose Card.
- Select a format for your card.
- The Choose Card Theme screen appears. At the top of the Photos window, a spinning activity icon indicates new themes are downloading. Wait until the icon disappears and all themes are downloaded before you choose a card theme.