Mojave on an Unsupported 2010 iMac


Allen Davis

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This little problem is a doozy, and there’s a lot of details to impart, so this is going to be long.

I installed macOS Mojave on my 2012 iMac using DosDude1’s patches for installing on unsupported Macs, and for the most part, it has worked beautifully for me. In fact, this old iMac boots and performs faster than it did under Sierra or High Sierra. http://dosdude1.com/mojave/

Before the installation process, I had to boot into Recovery Mode and use the Terminal to disable the System Integrity Program (SIP), since this can’t be done otherwise, even if you log in as root. And I also wanted to be able to install my old Adobe Creative Suite 4 software, which is difficult to do by itself on any macOS since El Capitan.

The Mojave installation itself went flawlessly. I remain extremely impressed at how well this works on my machine. (There are issues with certain unsupported models which are dealt with extensively on DosDude’s website, along with many workarounds.)

The instructions give the procedure for creating a custom Install disk using a 16GB or larger USB thumb drive. I used a spare 3.5" 640GB HDD instead, connected to a NewerTech Drive Dock through a USB 2 port. It probably made the installation run faster than through a thumb drive.

The only thing I’ve seen that doesn’t work properly is “Light Mode.” This seems to affect every machine which uses this patch to install Mojave. In Dark Mode, it’s flawless. And Dark Mode has been one of Mojave’s greatest appeals to me.

Now the problem: I’ve discovered that I can no longer boot into Recovery Mode, even when booting from an external HDD with FireWire 800 or another HDD connected to a NewerTech HDD dock on the USB 2 bus, even though they otherwise boot normally, and they are/were clones of my internal SSD.

In Terminal, I can enter diskutil list and see that the Recovery Partitions does indeed exist on my internal drive. It shows up in any listing, no matter what disk I boot from. I just can’t access or boot from it.

Terminal Disk List.jpg


No matter what drive I try the Command-R with, I get the dreaded universal “Prohibited” sign (circle with the slash in it). After a few minutes, the iMac just shuts down.

I found an AppleScript on a MacWorld site which supposedly creates or enables a Recovery Partition, but it doesn’t work with Mojave (it lists macOS 10.9 and up, but obviously doesn’t include Mojave since I think it was posted in 2017).

Why this is important to me: I want to re-enable SIP because it’s Apple’s way of keeping malicious third-party software/malware from being able to access some really important stuff which can greatly compromise a Mac’s otherwise super-duper great security. But as I said before, SIP can only be turned on or off by logging in using the Recovery Mode. (You can see SIP’s status by using the Terminal command csrutil status, and it will say enabled or disabled. If you type csrutil enable or csrutil disable, you get this:

Terminal CSR Commands.jpg


This has really got me scratching my head. With all the brain power and experience here on MacHelp, I’m sure someone can steer me in the right direction!

FOOTNOTE: Mojave can be installed on a HFS+ Journaled drive, but doing so disables automatic macOS updates or notifications, and requires going through a long, convoluted install process similar to the one which put Mojave on your startup drive in the first place. So it's important to keep your customized Mojave Install disk around.

I have thought about the possibility of the Recovery Partition being accessible were I to go back to square one and install Mojave on my drive formatted as HFS+ Journaled and GUID. But as stated above, I want to be able to more seamlessly install future software updates.

I have also thought about starting over with APFS, but choosing the Apple Boot thingie partitioning option instead of GUID.

The actual installation process isn't too overly time consuming. It takes maybe an hour or two. It's getting all my data back onto the drive (with CarbonCopyCloner) that takes half a day.
 
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Cory Cooper

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Hi.

I wonder if it may have something to do with your iMac not being supported for Mojave? Maybe because the Model Indentifier or firmware isn't supported, it won't allow it to startup in Recovery?

Honestly, I would contact the author of the patch tool. I am sure they have run across this before. I have no experience with these types of hacks unfortunately.

C
 
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Allen Davis

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Hi.

I wonder if it may have something to do with your iMac not being supported for Mojave? Maybe because the Model Indentifier or firmware isn't supported, it won't allow it to startup in Recovery?

Honestly, I would contact the author of the patch tool. I am sure they have run across this before. I have no experience with these types of hacks unfortunately.

C
Thanks for the reply. I'm not a coding-type of guy, so I certainly can't read it. But I'm pretty sure that DosDude probably wrote new firmware, or at least did something to the existing firmware. There are numerous things he had to "patch" in order to get Mojave to run on unsupported machines.

I was contemplating the purchase of a new iMac simply because I didn't want to cling to an older machine for anywhere as long as I desperately clutched my 2002 1.25GHz G4 MDD (which I still have over in the corner, simply awaiting the press of the power button). Then I ran across this Mojave patch and it caught my eye. And since I was thinking about buying a new iMac, I thought, what the heck. If the very worst thing were to happen, like bursting into flames, I still had my MBP to fall back on.

After a failed first attempt, which was my fault by failing to follow instructions, I got Mojave installed in almost no time. Reinstalling all my data was another thing. Even with CCC, it took nearly a half day. I cringe at the thought of how long it would've taken had I attempted to use a TimeMachine backup (which I don't keep for that very reason; I prefer multiple bootable clone drives instead.).

Various unsupported Mac models each have their own idiosyncrasies, most of which can be sidestepped. The only "universal" shortcoming is running in "Light Mode," in which the menu bar and sidebars are gray with black type and very little contrast. I've been using Mojave for a week now, and I haven't encountered a single hiccup of any kind. In fact, this machine actually boots faster now than it ever did with Yosemite, El Capitan, Sierra or High Sierra. The only modification I've ever made to this iMac was to max out the RAM and install a Mercury Extreme 500GB 6G SSD.

I haven't been able to fault this Mojave "patch" or its author with anything except the fact I think he should've stressed the importance of not using any version of Onyx other than the one matched to the OS version for which it was released.

I've attempted to contact DosDude, but I have yet to receive a response.

I really appreciate your advice. Perhaps there are other brave souls here who might make the attempt to upgrade their own older Macs and figure out a solution.

Off topic: Just curious, but what's become of Honestone? I haven't seen a post from him in some time. He and I had been engaging in a private correspondence, but I've not heard from him in a few months. And honestly, I'm a little concerned.
 

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