How to fix MacBook Air update stuck on Apple Logo

If your Mac never progresses beyond an Apple logo or progress bar:

• Press and hold the power button on your Mac for up to 10 seconds, until your Mac turns off. (Every Mac has a power button. On laptop computers that have Touch ID, press and hold Touch ID.)
• Turn your Mac back on. 
• If the issue persists, press and hold the power button until your Mac turns off. Then unplug all nonessential accessories from your Mac, including printers, drives, and USB hubs. You could have an issue with one or more of those devices or their cables. 
• Turn your Mac back on.
• If the issue persists, once again press and hold the power button until your Mac turns off. 
• Use Disk Utility to repair your startup disk.
• If the issue persists, reinstall macOS from macOS Recovery.

If your Mac is stuck to Apple logo or progress bar ⇢ If your Mac starts up to an Apple logo or progress bar - Apple Support

Aidenee Said:

"My macbook air update is taking over a day: My macbook update is taking over a day and also it only shows the apple logo on the black screen and there is no white gage bar that should show the progress of the update. What do i do to fix this problem??"

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If a Stalled Update:

A. Connect to a Router:

Have a router? Power of your Mac, and try this once more. For a Mac with no Ethernet port, and only USB-C ports,t this is the adapter to use: The Belkin USB-C to Gigabit Ethernet Adapter - Apple

B. Restore from a Backup:

Restore your Mac from a backup that that you created prior to this update. If your never made a backup, then take this as a learning experience, knowing to always to create a backup your Mac, prior to making any change to ii (i.e. an update install or application install). That way, you can have something to restore it from, shoud anything go working after the install.