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Sequoia installs on iMac 18,3 - NO OCLP

E

edweb

macrumors newbie
Original poster
Aug 29, 2021
12
1
I'm not quite sure what's going on here........was running my 2017 iMac 18,3 on 13.7.1 but yesterday I got an "Upgrade to Sequoia"-prompt via Software update in my System Settings.....so I clicked and, lo and behold, 15.4.1 installed and works fine - without any OCLP.

I had no idea that iMac 18,3 models were now natively compatible with Sequoia.....?

Screenshot 2025-05-04 at 11.43.24.png
 
The About window should show the year under iMac.
What Model Identifier is shown in the the System Information app? (/Applications/Utilities/System Information.app)
 
According to MacTracker, neither the 2019 or 2020 versions of the 27” iMac had a 4.2GHz option shown in the sceenshot. Also the Radeon Pro 580 was only offered on the 2017 model. So it looks like the OP’s iMac really is a 2017 18,3 which according to MacTracker can only run up to latest version of Ventura. The only 2017 iMac that is stated to run Sequoia is the iMac Pro.

Very odd.

OP have you ever used OCLP on this machine in the past?

If Apple has changed something I would expect a few other reports.
 
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bogdanw said:
The About window should show the year under iMac.
What Model Identifier is shown in the the System Information app? (/Applications/Utilities/System Information.app)
Click to expand...
I think the OP wants to deceive us! Normally the window displays the model & year under 'iMac', his screenshot is manipulated.

Here the Info from my iMac (5K, 2017)- but with OCLP:

imac.jpg


@Mike Boreham: The 4,2 GHz Intel Core i7 option is real…

Best regards,
banditDD
 
Last edited:
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Thanks, everyone. I can post system info when I'm back at the machine.

@ BanditDD - not sure why you'd think I would want to "deceive" anybody. I have a genuine question because I'm not tech- or Mac-savvy enough to understand what's happening.

@ Mike Boreham - Yes I previously ran the machine with Sonoma on OCLP. Due to some software incompatibility issues I eventually wiped the main hard drive and clean installed Ventura via Recovery (i.e. last officially supported OS version). After a few weeks I eventually got the Sequoia upgrade prompt. There couldn't have been any OCLP "leftovers", the hard drive was completely blank, and I did not use TimeMachine backups to re-install previous User, System or other related settings or files. It's basically a "new" machine. Yesterday I also downloaded the latest Sequoia Installer (via MIST), just to check if this was some fluke - and it downloaded and installed again, without issues.

This may sound silly, but is there any way that the machine got hacked / remote pirated or something......?
 
edweb said:
I eventually wiped the main hard drive and clean installed Ventura via Recovery (i.e. last officially supported OS version). After a few weeks I eventually got the Sequoia upgrade prompt. There couldn't have been any OCLP "leftovers", the hard drive was completely blank
Click to expand...
Erased the macOS volumes and/or APFS container? Or erased the hard disk with a new partition table? I am pretty sure the former which would not remove the OCLP modifications to the EFI partition. So you still have the OCLP EFI partition. You need to erase the hard disk so that a new partition table and EFI partition is created.
 
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gilby101 said:
Erased the macOS volumes and/or APFS container? Or erased the hard disk with a new partition table? I am pretty sure the former which would not remove the OCLP modifications to the EFI partition. So you still have the OCLP EFI partition. You need to erase the hard disk so that a new partition table and EFI partition is created.
Click to expand...
Adding to this, if the OP had completely erased the drive he wouldn’t have been able to start from Revovery to install the macOS. Recovery would have been wiped. I completely erased my drive once and the machine would not boot at all. I had to use Apple Configurator from a second Mac to put the firmware and hidden volumes back on.
 
Mike Boreham said:
if the OP had completely erased the drive he wouldn’t have been able to start from Revovery to install the macOS.
Click to expand...
Good point. But this is an Intel Mac, so it will work to use a bootable installer on a USB key.

edweb said:
was running my 2017 iMac 18,3 on 13.7.1
Click to expand...
So fix this: Download macOS 13.7.x (the latest) and create a bootable installer USB key. Boot it and erase the drive creating new partitions. Then install macOS and recover apps, settings and files from the most recent TM backup created under macOs 13.7.x
 
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Thanks everyone, obviously have some homework & cleaning up to do......
 
Mike Boreham said:
Adding to this, if the OP had completely erased the drive he wouldn’t have been able to start from Revovery to install the macOS. Recovery would have been wiped. I completely erased my drive once and the machine would not boot at all. I had to use Apple Configurator from a second Mac to put the firmware and hidden volumes back on.
Click to expand...
On an Intel Mac like this one, you can use internet recovery which works fine on a fully erased disk.
 
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Just to reconfirm this is issue is NON-EXISTENT because there was indeed some leftover OCLP installation on my HD, clearly I did not erase the entire disk as I had thought I did (thank you "gilby101" for the tip).

My apologies for saying or asking anything stupid.
 
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