I’ve been using my 2014 iMac 5K for more than a decade, and the 27-inch 5K screen is still a joy to use. Sadly, some of the apps I use on a daily basis will no longer work. Rather than buying a new Mac, I opted for a different solution that cost me nothing.

Microsoft 365 is about to lose support on my iMac

I’ll no longer be able to create, edit, or save new files

Credit: Lucas Gouveia / How-To Geek | warat42 / Shutterstock

My ancient iMac only officially supports macOS 11 and there are plenty of apps that will no longer run on Big Sur. Until now, none of them have been that important to me.

Unfortunately, that’s all now changing. I received an email informing me that although the apps will still open, from July 13, 2026, Microsoft 365 apps such as Word and Excel will run in “reduced functionality mode.” This means that I can’t edit, save, or create files using these apps. I use Word and Excel almost every day for work purposes, so this is understandably a bit of a problem.

Microsoft has an official policy of only supporting the three most recent versions of macOS, and macOS 11 Big Sur is already out of that window. What’s different here is that while Word and Excel haven’t been officially supported on macOS 11 for some time, they could still be used; this new change means that my Office apps lose their most important functionality.

The explanation from Microsoft is that a certificate used by Microsoft 365 apps to validate the Office license is expiring, affecting older app versions on macOS and iOS. Updating to macOS 12 or higher and then updating the Microsoft 365 apps should fix the problem. My issue is that macOS 11 is the highest supported version for my iMac, and I can’t update to macOS 12 through Apple’s update system.

OS

Windows, macOS, iPhone, iPad, Android

Brand

Microsoft

Microsoft 365 includes access to Office apps like Word, Excel, and PowerPoint on up to five devices, 1 TB of OneDrive storage, and more.

My Mac is capable of running unsupported versions of macOS

The hardware isn’t the issue

Credit: Krisda / Shutterstock.com

My iMac may be over a decade old, but it’s still a perfectly usable desktop computer. The Fusion drive died long ago, so the whole thing is running on an external SSD, but it’s still more than good enough for writing and research, which are the main things I use it for. The huge, beautiful screen is ideal for working with multiple apps at once.

Word and Excel run just as well on my iMac as they do on my MacBook Air M2, so the issue isn’t that the hardware isn’t up to the job. The problem is that avoiding the Microsoft 365 certificate issue requires macOS Monterey or newer, and while a late 2015 iMac supports Monterey, my 2014 model tops out at Big Sur.

Monterey isn’t that much heavier than Big Sur. The Late 2015 iMac 5K that could support Monterey had a newer Intel platform, faster RAM, and newer AMD graphics, but it wasn’t a huge leap in performance. Apple had to draw the line somewhere, however.

OpenCore Legacy Patcher lets me do what Apple won’t

Getting a 2014 iMac onto Monterey for free

The good news is that I don’t have to spend a small fortune buying a new computer just as Apple has announced significant price increases on many of its existing products. There’s an unofficial way to get my iMac to update beyond macOS 11.

OpenCore Legacy Patcher is a free and open-source project designed to enable Macs to boot and run newer versions of macOS than they officially support. When you run a macOS installer, the software looks at your hardware to see if it’s a supported model. If it isn’t, the installation won’t go ahead.

OCLP sits between the installer and your hardware, intercepts that request, and tells the installer, “Hey, don’t worry, this Mac is totally supported.” Once the OS has been installed, OCLP can apply post-install patches that restore support for older Mac hardware, so that the older graphics card on my iMac can handle what is being asked of it.

Using OCLP involves downloading an installer for the version of macOS you want to run onto a USB drive. The OCLP app then creates a macOS installer on the USB drive and installs the OpenCore bootloader to that drive. You then install the new version of macOS from that USB drive.

Once the updated version of macOS is up and running, installing OpenCore on the internal drive ensures that the Mac can boot normally without needing the USB connected.

My iMac is running Monterey without notable issues

It could potentially run even newer versions of macOS

Credit: Gouveia / How-To Geek | WML Image / Shutterstock

Some users reportedly have Late 2014 iMac 5K models running macOS Sequoia. The newer the OS, the more likely your Mac is to struggle, so I played it safe and stuck to upgrading to macOS Monterey. It worked like a charm, and I’ve had no major issues since the upgrade, although your mileage may vary.

OCLP isn’t perfect. macOS updates can wipe OCLP’s root patches, meaning you may need to reinstall those patches after updating.

My iMac is still clinging on

For now, thanks to OCLP, I’m still able to use Word and Excel, and it didn’t cost me a dime. At some point, I will have to say goodbye to the computer that’s served me so well over the years. I can’t help but hear the voice of Indiana Jones whispering in my ear, “It belongs in a museum!”