There are a few reasons why you might want to reinstall macOS (or even Mac OS X). Perhaps your Mac is working erratically and you think that a clean install of the operating system might fix the.
Last night, when attempting to restore three iMacs to a fresh Install of OS X, I was left with an annoying and slightly frightening message: “OS X Cannot Be Installed On This Computer.” For some strange reason, this happened to me on three different iMacs, all of which previously had Bootcamp partitions. So after a bit of brainstorming, I ended up fixing the issue by resetting the PRAM on all of the iMacs.
So, what is PRAM anyway? In the Mac world, PRAM stands for Parameter Random Access Memory. This memory is used to store info on your startup disk, startup volume, speaker volume, and timezone information amongst other vital system information. However, sometimes this memory can get skewed, causing problems and requiring a factory reset.
Resetting your PRAM is simple. First, completely shut down your Mac via the Apple Toolbar. Then, hold down Command, Option, P, and R buttons on your keyboard as you restart your Mac. Continue to keep these buttons held until you hear the Mac startup chime twice. After the second chime, let go of the buttons and let your Mac restart as normal. No user data will be lost in this process.
Resetting your PRAM will not only fix this particular OS X install issue, but it can also fix network issues, sound issues, and display issues. So next time your Mac is acting wonky, reset the PRAM and it should be back in working order.
Image Source: felixtriller