Running macOS High Sierra 10.13.6 does not mean you have to be locked out of Xcode development. While you cannot install the latest version from the Mac App Store, you have a clear path forward: download Xcode 10.1 or Xcode 9.4.1 directly from Apple's developer website.

By following this guide, you can continue to maintain legacy apps, learn Swift 4.2, or build tools for older Macs. Keep your High Sierra machine running efficiently, and always keep a backup of that Xcode_10.1.xip file on an external drive — because Apple may remove it from their servers in the future.

Follow the same steps to log into the Apple Developer Downloads page. Search for Command Line Tools macOS 10.13 . Download the .dmg file matching Xcode 10.1.

The download may take a long time depending on your internet speed. The .xip file is a compressed archive. Ensure your browser does not go to sleep during the download. It is highly recommended to use a download manager if possible.

Download from the official Apple Developer portal. Use Archive Utility to unpack the .xip file. Drag the final app into your Applications folder.

Are you running macOS High Sierra (version 10.13.6) on an older Mac but need to install Xcode for development? You have likely encountered a frustrating problem: opening the Mac App Store, searching for Xcode, and seeing an error message stating that "Xcode can't be installed on 'Macintosh HD' because macOS version 10.15.2 or later is required". This is a common issue for users of this operating system.

As noted in developer documentation, "to have more than one version of Xcode: simply name them differently on the Mac".

Navigating the complexities of legacy software on older operating systems can be challenging. The essential step is to bypass the modern Mac App Store. Instead, you should always download the precise, compatible version of Xcode directly from Apple's official developer archive. This method bypasses the compatibility blocks and gives you direct control over your development environment.

Locate the downloaded Xcode_10.1.xip file in your folder.

If all checks pass, you have successfully completed the mission.