During macOS installation, the Apple logo or progress bar might remain onscreen for much longer than usual after your Mac restarts. As installation continues, the progress bar might move slowly and pause for long periods. That's why Apple recommends beginning macOS installation in the evening—so that it can complete overnight, if needed.
If your Mac seems stuck on this screen
If you feel that you've waited long enough to know that the installation process will not continue, follow these steps.
- Press and hold the power button for up to 10 seconds, until your Mac turns off.
- Unplug all accessories from your Mac, including printers, drives, USB hubs, and other devices. (You could have an issue with one or more of those devices or their cables.) Then turn your Mac back on.
- If your Mac still doesn't finish starting up, follow the steps to reinstall macOS from macOS Recovery.
If you need help
If you can't reinstall macOS, or reinstalling doesn't help, please contact Apple for support.