big sur 11.6 update hangs on startup

Macbook Air with Apple processor. Ran the scheduled update for 11.6 OS overnight. Laptop now will not progress past login. After the login I get a black screen, apple logo and progress bar stuck at <5%.

Have left it to run for 3-4 hours - no change.

Followed the "standard" instructions - e.g. restart, disconnect all devices. - no change

Started in Recovery Mode - Can't reinstall 11.6 as it recognises it has already been installed on the disk and get a "can't downgrade OS on disk" message.

Frustratingly we pay for AppleCare support and their advice is, ultimately to reformat the disk. That would be my last resort option .

Appreciate any ideas.

MacBook Air (2020 or later)

Posted on Sep 16, 2021 3:03 AM

Reply
1 reply

Sep 16, 2021 4:31 AM in response to MacSuffolk

Again - shutdown computer by any means required including the Power Button.


Disconnect all external devices.


Connect the charger.


Restart and immediately Hold the SHIFT key and keep holding until Apple Logo is presented - then, release.


This is Safe Mode.


It will do a Repair Disk, clear system cache files and only load Apple Software, extensions and fonts.


This may or may not allow the update process to complete - hopefully successfully.

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big sur 11.6 update hangs on startup

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