After accepting the latest security update, my iMac (running macOS 10.15.7) froze on boot. Restarting replicated the freeze. I have gone into recovery mode and started a time machine restore (10 hours - sigh).
Assuming the restore works, what are my options for implementing the security update? Has anyone else seen this?
iMac Line (2012 and Later)
Unfortunately, the restore might be restoring whatever conflicted with the MacOS and caused the freeze in the first place.
Since you have done the restore, when it is done, try booting in Safe Mode (hold shift key during restart, may have to wait 10-25 minutes for the Safe Boot to complete). After booting into Safe Mode, trying applying the update from there (from Safe Mode).
If you run into the same problem again, a different approach will be needed. Before embarking on this, you should have at least one, preferably two valid and working backups. It sounds like you have one. Two would be better, just in case.
(1) Boot into Recovery (COMMAND-R)
(2) Erase/reformat your disk
(3) Reinstall the MacOS.
(4) On first boot do not migrate from your backup. Instead create one new administrator user with a different username from any of your previous accounts.
(5) With that admin user, apply all the updates including the security update.
(6) If it fails again, it is most likely hardware because you are working with a computer that is configured as if it was factory new, with nothing but the native Apple software.
(7) If it succeeds, then migrate from your backup only user accounts, files and documents, but no applications and no settings or anything else.
(8) If you have gotten this far and everything is ok, start reinstalling your software one or two at a time. Restart after each install to test normal booting and operation. Something you had previously installed may have been conflicting with the update and/or MacOS, hence the caution.
I saw this once with a 2010 MacBook Air (on High Sierra). The above process resolved it. That MacBook Air is still running.
If you had any security, anti-virus, or "cleaner" software/utilities previously, don't reinstall them. If the Safe Mode technique works, then uninstall any or all software you have that is like any of these.
Unfortunately, the restore might be restoring whatever conflicted with the MacOS and caused the freeze in the first place.
Since you have done the restore, when it is done, try booting in Safe Mode (hold shift key during restart, may have to wait 10-25 minutes for the Safe Boot to complete). After booting into Safe Mode, trying applying the update from there (from Safe Mode).
If you run into the same problem again, a different approach will be needed. Before embarking on this, you should have at least one, preferably two valid and working backups. It sounds like you have one. Two would be better, just in case.
(1) Boot into Recovery (COMMAND-R)
(2) Erase/reformat your disk
(3) Reinstall the MacOS.
(4) On first boot do not migrate from your backup. Instead create one new administrator user with a different username from any of your previous accounts.
(5) With that admin user, apply all the updates including the security update.
(6) If it fails again, it is most likely hardware because you are working with a computer that is configured as if it was factory new, with nothing but the native Apple software.
(7) If it succeeds, then migrate from your backup only user accounts, files and documents, but no applications and no settings or anything else.
(8) If you have gotten this far and everything is ok, start reinstalling your software one or two at a time. Restart after each install to test normal booting and operation. Something you had previously installed may have been conflicting with the update and/or MacOS, hence the caution.
I saw this once with a 2010 MacBook Air (on High Sierra). The above process resolved it. That MacBook Air is still running.
If you had any security, anti-virus, or "cleaner" software/utilities previously, don't reinstall them. If the Safe Mode technique works, then uninstall any or all software you have that is like any of these.
macOS Catalina 10.15.7 1 Feb 2021 Security update boot issue
