I have a serious problem with my 2017 iMac running macOS Catalina BETA. After a normal reboot the iMac loaded until the bar reached 100%. Then for hours nothing happens, it just stays at 100%.

The things I tried:

  • Boot in Safemode - still hangs on 100%, can’t access Safemode
  • Reset NVRAM/PRAM - nothing happened
  • Reset SMC - nothing happened
  • Run First Aid on all disks - helped and discovered nothing
  • Uninstalled Google Chrome update in terminal - nothing happened
  • Tried to reinstall MacOS Catalina - not enough space on my disk
  • Tried these commands: cd /Volumes/Macintosh\ HD/var/db/caches/opendirectory and mv ./mbr_cache ./mbr_cache-old - “no such file or directory”
  • Tried to boot in startup manager - still hung on 100%
  • Tried to run the Apple diagnostics - it said everything is fine
  • Single user mode with commands like mount-uw / - command not found
  • Let the iMac sit for a couple days - still hangs on 100%

And so on…
So, as you can see, I tried many things and nothing helped. Do you have a good solution or a advice/suggestion without erasing the disk?

1 Answer 1


Apple has a very good triage step that I follow even after doing a very good job like you in trying to eliminate things (or hope for a quick fix)

Why not start down that path and this evening make a good last backup so you can proceed where it says erase and start over?

  • 1
    Thank you for your research bmike! After I tried so much I also came to the conclusion, that the best way would be just to get the backup on the drive and delete the buggy one (luckily I had a backup from like two months ago). Now everything works just fine and I didn’t lost really important data. The moral from this case is: do backups FREQUENTLY. Thanks allot for your help! Take care and best regards, Aaron
    – Freshron
    Nov 6, 2019 at 23:04

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