Reinstall macOS

If you need to take the extreme step of reinstalling macOS Sierra, you can do so using Recovery mode. You can choose to erase the drive and start fresh, or simply replace macOS and leave your documents and apps alone. This is handy for fixing extreme problems or before passing the Mac along to a family member.

Comments: 19 Responses to “Reinstall macOS”

    Patrick Davies
    8 years ago

    Thanks, Gary, great video as always. I may be selling my MacBook Air to my neighbour and it would be nice to have the latest OS on the laptop rather than the original factory installed OS. As long as I delete all my accounts, is there any reason why I can't go for this option rather than the one outlined in yesterday's video which used internet recovery?

    8 years ago

    Patrick: If you install the latest OS, or leave it on there, it will be registered to YOU. The "download" for the OS will be under your name and Apple ID. This will cause him trouble (and maybe you too). Best to roll it back to the original OS. Then he can log in and do the upgrade to Sierra right away. You can help him with that if you want.

    Michael Simms
    8 years ago

    Why not use an install disk created from macOS Sierra install program??

    8 years ago

    Michael: Disk? Macs don't come with optical disc drives anymore.

    Nassar
    8 years ago

    Love those vids Gary! I have a question though, what if I download Sierra from the App Store using My Apple ID then create an installer USB flashdrive from that Mac OS Sierra.app, will this installer register under my apple id on any mac I install it on? (I did this to one of my mac mini's which I already sold).

    8 years ago

    Nassar: Not sure, sorry. I would assume so, but I can't say without trying it.

    rhkennerly
    8 years ago

    Gary, did I muss the part about reinstalling the os while leaving your files & apps intact?

    8 years ago

    rhkennerly: If you just reinstall the OS, then that is what you get. So DON'T do the erase the disk part. And, as always, back up first.

    Nassar
    8 years ago

    What if I try doing it on like a random mac. How would I know or check if my Apple ID is registered to the OS?

    Thanks alot.

    8 years ago

    Nassar: Not sure. Hard to test. I don't think it will, but I can't find any source that says either way.

    Lee
    8 years ago

    If I install a new macOS Sierra to my old 2011 MacBook Pro and clean out as a new computer, will all on the install app's be downloaded with the install? As, launchpad, Siri, Safari, App Store,ibooks, FaceTime, etc?

    8 years ago

    Lee: Those "apps" you mention are part of macOS (Siri, Launchpad, Safari, App Store, iBooks, FaceTime). Other apps, like iMovie, Pages, etc, are separate apps. If you clean the drive and just install Sierra, you will only get Sierra (which includes those apps I mentioned). Other apps, like iMovie, you would simply download again from the App Store once you are done installing Sierra.

    Glynne
    8 years ago

    Gary, my 5yr old i5 16Gb iMac is significantly slower than when I got it. Very slow when you login or switch users (can literally take 2 minutes before it becomes fully responsive). I've got plenty of disc space left - would doing a reinstall without erasing my files and apps help? Or is there other things I should be looking at?

    8 years ago

    Glynne: You should take it to an expert (Genius Bar) if you can't diagnose it yourself. Reinstall may not help, or may only be a temporary help. Better to find out what is really going on.

    Glynne
    8 years ago

    Hi Gary, would like to do that but unfortunately NZ doesn't have an Apple Store yet. I think I'll try a reinstall and see what happens.

    Squafdonoboles
    8 years ago

    Now I'm REALLY confused. How many operating systems for MACs are there?

    8 years ago

    Squafdonoboles: Not sure what you mean by that question. Every year Apple comes out with a new version and gives it a name. The current one is 10.12 and is called Sierra. Before that we had El Capitan (10.11), Yosemite (10.10), Mavericks (10.9), etc. Each one has brought new features to OS X (now called macOS).

    Nick Moye
    8 years ago

    I have an older macbook that has OS X 10.6.8 I want to reinstall OS only, not a complete install. I didn't see any video on how to do this with my current OS.
    Can you please show/tell me how to do this? My current problem is that the beach ball shows up almost as soon as I get to main screen and just will not stop.. Have tried Apple tech and they say it's to old to work on...
    Thanks

    8 years ago

    If your Mac is old enough to have an optical drive and use Snow Leopard (10.6) then you would do the reinstall by booting from the Snow Leopard disc.

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