Why can't I upgrade a 2015 iMac to Monterey? It's listed as being a compatible operating system

Tech Support
1

I picked up a used iMac 5k mid 2015. Apple’s website states that the latest compatible operating system is Monterey.

-Apple’s serial number lookup verifies the model, but it only let me upgrade it to Big Sur:

-I have plenty of disk space, so that isn’t the issue.

-I found that Monterey is no longer available in the App store, so I downloaded the installer from https://mrmacintosh.com/macos-12-monterey-full-installer-database-download-directly-from-apple/ which is apparently a well known source. I tried installing from within Big Sur and got the error message above.

-I made a bootable USB with the image from above, tried to upgrade that way, but got the :no_entry_sign: boot window, indicating the operating system was not compatible.

-The seller had performed a clean install when he gave it to me, and it was running Yosemite. I was able to upgrade to Big Sur from a download at MrMacintosh, but not to Monterey.

I’m at a loss. Why can’t I upgrade?

2

It says here…

… that Monterey is only compatible with the Late 2015 model of the 27-inch Mac, not the Mid 2015 one.

The information on the page from the screenshot is probably incorrect (as some Apple Discussion posts also conclude if you search a bit). You may want to try OCLP, though.

3

Ah, I was using Identify your iMac model - Apple Support which indeed is contradicting to the link you provided. I was hoping to avoid OCLP as I’ve always had graphical issues with other iMacs.

Thanks for resolving this.

4

Mactracker also reports that the Mid 2015 iMac supports up to Big Sur only so that’s apparently a mistake on Apple’s Identify your model page.

(I’d post an image from Mactracker, but there’s still an issue with posting images here.)

Welcome to the MPU forums, by the way!

5

That’s a bummer. I have a Late 2014 Mac mini that is running macOS Monterey 12.7.5