reload latest high sierra

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Level 1

8 points

reload latest high sierra

I have been having problems with a very slow iMac (2013). It suddenly became slow and is slow for all users. It is slow to start, log in and use.

I tried to use AVG antivirus to do a deep scan but after scanning overnight, only 8% of the computer had been scanned (3TB HD with 1TB free).

When I tried to restart it, the computer started with a do not disturb symbol. After searching online I discovered to restart holding down the Command and R buttons then using the disc utility to repair the disc which went well and I also used verify for the OS.

I then tried to reload the OS (using and ethernet connection) but was given the message that I could not reload because the version of OS that I was using was newer than the version that I was trying to reload.

I can't see which version of OS I am using( I assume it is the latest as I always keep it upto date) as my mouse cursor has disappeared (batteries are new and the green light is showing on the mouse).

The activity monitor is not working today but yesterday it showed activity levels towards the bottom of the graph.

Is there another way I can reinstall the OS, or should I just find a repair shop and take it in. The nearest Apple shop is a couple of hours away.

Thanks for any help

iMac Line (2012 and Later)

Posted on Jan 7, 2019 1:44 PM

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Answer 1

Best reply

John Galt

Level 10

141,216 points

Jan 7, 2019 3:58 PM in response to timball

If a Mac starts performing poorly the very last thing anyone should do is to install some "anti-virus" junk. There are no macOS viruses and there never will be any. "AVG" is garbage, as are all similarly categorized products. Rule 1 of Macs is don't install junk.

The reason your Mac began operating poorly was very likely due to hard disk drive failure. Any "repair" performed by Disk Utility is likely to be temporary, since whatever caused the failure is 100% certain to occur again.

The "prohibitory symbol" means the Mac cannot find an operating system to load. Reinstalling macOS is required, and described here: Reinstall macOS - Apple Support. Use either the first or third options in Step 2, the choice being whether you want to update macOS to the latest version that will run on your iMac, or the version already installed on the local Recovery Partition.

The second option won't work for the reasons you explained. None of the options will work if that Mac's startup disk is corrupted—which seems likely to me, given your description of the events. The appropriate action in that case is to repair or replace the Mac, followed by restoring a Time Machine backup.

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Answer 2

timball Author

Level 1

8 points

Jan 16, 2019 12:16 PM in response to John Galt

Hi John, thanks for your help. I took it to an Apple authorized repairer and the ran a test which confirmed that it was a disc problem. They haven’t got back to me yet regarding if the disc can be saved but I am assuming that I’ll need to replace the disc. Thanks for your help.

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reload latest high sierra

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