Every few restarts, Mac won't start up, unless I reset PRAM

Discussion in 'macOS High Sierra (10.13)' started by Gary King, Feb 20, 2018.

  1. Gary King macrumors 6502

    Jun 14, 2004
    For some reason, every few times (let's say every 5 times) I restart my Mac Mini (running MacOS High Sierra 10.13.3, on an SSD), the startup screen will get stuck on the white loading bar with a black background, with the white bar at 100% full and just sitting there for minutes (the longest I left it on that screen is about an hour, and I wasn't willing to wait any longer).

    If the startup screen is stuck, and then I force my Mac off and turn it on, then it just gets stuck there again, once the loading bar reaches 100%. The only way to bypass this is to reset my Mac's PRAM. Then when I start up the Mac again, it loads fine.

    Why does this happen? And how can I fix it? Unfortunately, I'm not sure when this started happening, since I rarely restart my Mac, except when I update it. I only Sleep my Mac every night.

    My Mac's memory is actually brand new (it's a few days old), and I have already ran a Mac Hardware Diagnostic anyway, and it said there were no problems.
  2. techwarrior macrumors 65816


    Jul 30, 2009
    Any chance you have some old drivers (kext) on your system that are no longer supported?

    A while back, I had issues with a Mini I restored from a hackintosh backup and when I upgraded, System Integrity prevented these from loading, thus stalling my boot up.

    To fix it, boot into Safe Mode (hold SHIFT while booting). Safe mode bypasses loading third part drivers (usually). Open Terminal, and find all non-apple Kexts:

    kextstat | grep -v com.apple

    In the resulting list, you will find low level drivers for things like AntiVirus, Virtualization software (VMWare, Parallels, Virtual Box), and other things that might be non-native. Start with the most obscure items, delete them and then see if that fixes it. Repeat until you are healthy again. In particular, if there was an app or hardware you recently installed, this would be the most likely culprit.

    To unload a kext, assuming it is in /System/Library/Extensions (most are here):

    sudo kextunload /System/Library/Extensions/NAME_OF_THE_KEXT_FILE.kext (provide your Admin account login when prompted)

    Then, remove the kext folder using:

    sudo rm -r /System/Library/Extensions/NAME_OF_THE_KEXT_FILE.kext

    Then reboot normally.
    --- Post Merged, Feb 20, 2018 ---
    BTW, PRAM reset, like Safe mode, bypasses loading third party kexts in the boot process, waiting instead until the app launches (either manually or in your login items).
  3. fisherking macrumors 604


    Jul 16, 2010
    ny somewhere
    new ram? seems too coincidental that the problem is happening with the new memory. as much a nuisance as it is... you might put the original ram back in, see if the problem persists (or not).
  4. techwarrior macrumors 65816


    Jul 30, 2009
    Agreed, but if he rarely reboots and has the issue 1/5 times, this has been going on for a while. The memory was upgraded just a few days ago, so not likely the issue. Nevertheless @Gary King this is not a bad suggestion if it correlates to your problems.

    One more thing you can try is to boot into recovery, and re-install the OS (don't reformat the drive). What this will do is ensure you have good OS System files that might have become corrupted. Your apps, settings and files will remain in tact if you don't reformat the boot drive.

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3 February 20, 2018