Fixing 'Operating System Not Supported' Error in OCLP on iMac 2014

Fixing "Operating System Not Supported" Error When Launching OCLP

If you are trying to run the OpenCore Legacy Patcher app on an iMac Mid 2014 and you are met with an "Operating system is not supported" error, it means the version of macOS currently running on your iMac is too old to run the modern OCLP application itself.

Why does this happen?

The graphical user interface (GUI) version of OpenCore Legacy Patcher requires macOS 10.10 Yosemite or newer to run, and certain modern features require macOS 10.13 High Sierra or newer. If your iMac was factory reset and is running OS X 10.9 Mavericks or an early version of Yosemite, OCLP will refuse to open.

Step-by-Step Fix:

1. Option A: Update Natively First
   Your iMac Mid 2014 officially supports up to macOS 11 Big Sur. Open System Preferences > Software Update, or open the App Store and search for "macOS Big Sur". Install the native update first. Once on Big Sur, OCLP will open perfectly.
2. Option B: Use Another Mac
   If you cannot update natively, use a different, newer Mac to download OCLP, create the macOS installer USB, and build OpenCore onto the USB. Then, plug that USB into your 2014 iMac, hold the Option key whilst turning it on, and boot from the USB.
3. Option C: Download an Older OCLP Version (Not Recommended)
   Older, command-line only versions of OCLP supported older OSes, but they do not support modern macOS releases like Sonoma or Sequoia. Do not use this method if you intend to install a modern macOS.