After I put my MacBook to sleep, like I always do; the following day, I open the lid and it’s off for some reason. I turn it on and it powers up. I select my user account and enter the password. It loads and then freezes/hangs about half way through. It then reboots and loads some weird screen saying and macOS installation failed either restart, shut down, show log/save log.

What the is that exactly? Did my OS got corrupted for some reason? What should I do now?

  • Do you want to just wipe and install a clean OS (optionally loading from a backup if you please) or go through the steps to troubleshoot an os that doesn’t fully boot? Both are pretty common scenarios here and Apple has official guides how to step through both.
    – bmike
    May 12 '18 at 11:48
  • @bmike well, I’m not sure, I need to make sure I do not loose any files or anything? I would want to restore it all, so whoch option should I go with? And why does this happen?
    – Limpuls
    May 12 '18 at 11:50
  • 1
    If you're running High Sierra with apfs and can boot into Recovery, I would check out restoring from a local snapshot. Even without a TimeMachine backup, the OS makes a local snapshot before any update/installation.
    – Redarm
    May 12 '18 at 12:10
  • @Redarm if it makes snapshot after every update (I had an update 2 days ago), why time machine system restore in recovery screen doesnt find anything? How can I install the OS with one of the shapshots?
    – Limpuls
    May 13 '18 at 8:38
  • @Limpuls It could have been deleted already. There is space and time based "thinning". If free space is low, no snapshots will be kept for long.
    – Redarm
    May 13 '18 at 10:19

If you can boot to Recovery HD, then you can check for a local Time Machine back up or external drive backup and make a decision.

  1. Data is most important, so take the Mac to another Mac and use target disk mode or an external drive to get a known good backup off the drive. This assumes your drive or the Mac is failing and this isn’t just a software error and time you spend looking at the logs or trying to fix it delays the chance to save your data on a good drive.
  2. Dig a little into the error and try a reinstall of the os. This assumes the data is intact and you’re Ok risking loss and playing the odds.
  3. Find a technician or spend time learning about the console and boot process and specific boot error (see the logs or boot in verbose mode) to remedy a specific failure in the startup process.
  • Time machine system restore probably doesn’t have any backups. There is one disk my main one, I click it and searching for backups for like 5min now and still nothing. I will probably will have to go with reinstall OS, but can I expect to reinstall and not delete everythig I have? Also I can’t use another mac because neither I or anyone else I know have one.
    – Limpuls
    May 13 '18 at 8:35
  • @Limpuls unless you have hardware errors or an unlikely disk for,at corruption, the reinstall tries to never delete any user data. Basically, it’s safer than walking across the street in the US but not as safe as flying commercially in the US.
    – bmike
    May 13 '18 at 18:52

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