Your Mac doesn’t support the version of macOS you’re trying to install.There are several reasons you might see this error message. Why does “macOS could not be installed on your computer” appear? But if you don’t want to use Time Machine, create a bootable clone of your startup disk using a tool like SuperDuper or Carbon Copy Cloner. It’s best to do the backup using Time Machine, as you can then use Recovery Mode to restore your Mac from the backup. One of the steps described below involves a complete reinstall of the operating system, resulting in erasing data from your drive. It’s essential that before you perform any major upgrade, say from Catalina to Big Sur, that you backup your Mac. Before you try to install a new version of macOS But it can quickly become frustrating if, instead of being presented with a brand new Mac, ready to use, you see an error message like “macOS could not be installed on your computer.” Fortunately, you can do lots of things to fix the problem, so let’s get started. But to help you do it all by yourself, we’ve gathered our best ideas and solutions below.įeatures described in this article refer to the MacPaw site version of CleanMyMac X.Ī new version of macOS is always exciting. So here's a tip for you: Download CleanMyMac to quickly solve some of the issues mentioned in this article.