Macs running unsupported macOS versions are out of compliance and considered an unacceptable security risk.
ITS recommends upgrading to macOS 26 (Tahoe) or macOS 15 (Sequoia), depending on hardware support.
Use Software Update to download and install macOS. It’s faster, easier, and uses less storage space than other installation methods, and it shows only software that is compatible with your Mac. You can use Spotlight in the menu bar to search for “Software Update,” then open it from the search results.