My iMac will not load in operating system

[Bob M.]

I usually shut down my Mac about every two/three weeks or so. Yesterday, when trying to start it up I got an unusual error message : Mac OS is not loading in. And then it opened Mac Installer. I tried a few things and couldn't get it to work at all. I don't really know what to do. I can get my start page to show up at all. I've tried re-starting my iMac a few times with no luck. It's an older iMac but it still satisfies all my minimal computer just fine. I'm running Mac OS iMac High Sierra Mac OS 10.13.6.
Any ideas to get get me up and running again?

 

[MacInWin]

Do you have backups? From your description, the first suspect is that the internal drive has died.

 

[Rod]

Either that or the operating system has become damaged but given the message more likely the drive itself. When the OS is damaged (corrupted) you will see an Apple with a circle and diagonal line across the Apple image.
If the device was operating okay, no other problems, then you might consider installing a new Hard Drive, preferably a solid state (SSD).
Hopefully you have a backup or you data may well be lost.

 

[pm-r]

Any ideas to get get me up and running again?

I'm guessing the previous suggestions by Jake and Rod are valid but have you tried holding down the option key while booting up from a cold boot?

I was just wondering if its PRAM battery has finally died as I am assuming it's an older iMac.



- Patrick
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[Randy B. Singer]

Any ideas to get get me up and running again?

Boot up in Internet Recovery Mode (you, of course, have to have an Internet connection for this to work), go into Disk Utility, and run First Aid. Hopefully that will fix what ails your Mac.

For an Intel-based Mac:
https://support.apple.com/guide/mac-help/use-macos-recovery-on-an-intel-based-mac-mchl338cf9a8/mac
Startup using: Option-Command-R

For a Silicon-based Mac:
https://support.apple.com/guide/mac-help/macos-recovery-a-mac-apple-silicon-mchl82829c17/mac

 

[OliviaClaire]

I usually shut down my Mac about every two/three weeks or so. Yesterday, when trying to start it up I got an unusual error message : Mac OS is not loading in. And then it opened Mac Installer. I tried a few things and couldn't get it to work at all. I don't really know what to do. I can get my start page to show up at all. I've tried re-starting my iMac a few times with no luck. It's an older iMac but it still satisfies all my minimal computer just fine. I'm running Mac OS iMac High Sierra Mac OS 10.13.6.
Any ideas to get get me up and running again?

It sounds like your iMac is encountering a startup issue, possibly related to the operating system or disk problems. One thing you can try is booting into Safe Mode by restarting and holding down the Shift key, which may resolve the problem by performing basic checks and disabling unnecessary system extensions. If that doesn't work, boot into Recovery Mode using Command + R during startup and use Disk Utility to check and repair your startup disk for errors. If the issue persists, consider reinstalling macOS from Recovery Mode, which can sometimes fix software-related problems without affecting your personal files. Additionally, resetting the NVRAM/PRAM by holding Command + Option + P + R during startup might help. If none of these steps work, running hardware diagnostics using Apple Diagnostics or Apple Hardware Test could identify any underlying hardware issues. If the problem persists, contacting Apple Support or visiting an authorized service provider may be necessary for further assistance.

 

[Bob M.]

Thank you for that very thorough reply. Although I have tried many if not all the things you suggested here, what seemed to work was that I found out that my iMac has its serial number and other identification information printed on the underside of its computer stand. So, I unhooked everything (cables and whatnot), got the information from the underside of the stand, gave the machine a moderate shake and re-set it up. This time I got a alias of the internal hard drive which I clicked and, lo and behold, it booted up just fine. I haven't turned this computer off since. The first thing I did, once I got the desktop back was to run Time Machine and backed up everything.

I theorized that my internal drive on this older machine, which is part mechanical and part electronic, I must've done something to the mechanical part while tipping it upside-down to make it work. I bet they don't teach that one in computer repair class.

 

[Randy B. Singer]

...gave the machine a moderate shake ...

I theorized that my internal drive on this older machine, which is part mechanical and part electronic, I must've done something to the mechanical part while tipping it upside-down to make it work. I bet they don't teach that one in computer repair class.

Yes, it comes up all the time. Older rotating disk hard drives can suffer from something called "sticktion" (sticky friction). Usually putting it a very warm (but not hot) oven will unstick it long enough for you to back it up. Shaking it is NOT recommended because it might cause the read/write heads to bounce off the platter and damage the platter irrevocably.

It's good that you quickly made a full backup. It sounds like your Mac is very old and that your hard drive is on it's last legs.

It sounds like you are wary of shutting down your hard drive...and you should be. Usually a rotating disk hard drive, when it finally fails, will shut down and never boot up again.

 

[pm-r]

Yes, it comes up all the time. Older rotating disk hard drives can suffer from something called "sticktion" (sticky friction).

That reminds me of being introduced to a very well-respected local Mac repair Tech who was just about to fix a Mac Classic with just such a problem with a sharp wack with a large rubber mallet on the side of the Classic back in the late '80s. I was quite impressed as the Classic sprung back to life. I don't think it was a recommended Apple Macn repair....



- Patrick
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[MacInWin]

In addition to Randy's excellent reference to it, stiction generally happens when the drive is not rotating, so if you ever shut down the Mac, or if it loses power, stiction will most likely happen again, gettiing stronger each time. The cause is that the heads get too close to the disk itself and when not rotating, they can stick together very tightly. Once stiction starts, it progresses, never recedes. The drive is dying. Make a backup as quickly as you can and then decide what you are going to to--replace the drive or replace the iMac. That drive is on it's last legs.

 

[pm-r]

In addition to Randy's excellent reference to it

Excellent advice Jake.

And make a clone or backup as soon as possible while it is still rotating and able to work.



- Patrick
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