iMac will not upgrade past Yosemite

I have a 27" mid-2015 iMac that I want to upgrade to Sierra. (That's as high as I can go and still use some legacy software I need for work.) I have downloaded the Sierra InstallOS.dmg package, run the installation, and get the message "The software was successfully installed."

However, when I reboot, I check "About This Mac" and it says I'm still running Yosemite. I repaired disk permissions, but that didn't help.

Any advice on how I can get Sierra to actually stick, and boot?

iMac Line (2012 and Later)

Posted on Feb 8, 2021 12:15 PM

Top-ranking reply

Eau Rouge

Level 8

42,656 points

Posted on Feb 8, 2021 10:21 PM

Yes the installation window is misleading, it does not install macOS Sierra.

What it does do is create the Install macOS Sierra.app in your Applications

folder. Double-clicking on that will start the installation of macOS Sierra.

Your 2015 mac can actually upgrade to newer OS's such as,

macOS High Sierra 10.13, macOS 10.14, macOS Catalina 10.15 and the latest macOS Big Sur 11.0.

You would need to check your apps to see if they have updates available to work in the newer OS's.

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iMac will not upgrade past Yosemite

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