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How to Perform a Clean Installation of macOS Sierra

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macrumors bot
Original poster
Apr 12, 2001
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macOS Sierra is Apple's latest desktop operating system, which succeeds OS X El Capitan and adopts a new name to bring it in line with iOS, watchOS, and tvOS. The OS will come pre-installed on all new Macs once current stock is depleted and is a free download for existing Mac owners.


The main new feature in macOS Sierra is deep Siri integration, bringing Apple's personal assistant to the Mac for the first time. It also adds new features to Photos and Messages, and includes Continuity smarts like Universal Clipboard and an Auto Unlock option for Apple Watch owners.

This tutorial explains how to download macOS Sierra and perform a clean install, which offers several benefits over the automatic upgrade process included in the installation package.


Click here to read more...

Article Link: How to Perform a Clean Installation of macOS Sierra
 

Donald McGuinn

macrumors newbie
Aug 19, 2016
19
29
With every macOS update, I always perform a clean install. It is easy for me too because I have everything sync with Dropbox so it is almost like constantly backing up your computer.

Never have to worry about lost files. Finished my clean install last night.
 

merkinmuffley

macrumors 6502a
Dec 3, 2010
615
581
Good set of instructions, thanks.

Last time I used SIRI I wanted to toss my phone out the car window. It won't be installed on either of my Macs.
 
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petitpiton

macrumors member
Mar 6, 2009
55
27
UK
"sudo /Applications/Install\ macOS\ "macOS Sierra.app"/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ "macOS Sierra.app" --nointeraction"

methinks you mean:

sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ Sierra.app --nointeraction
 

NervousFish2

macrumors regular
Mar 23, 2014
244
330
Is this really worth doing? I have "dirty" upgraded since I got my MBP in 2011 and not noticed any issue so far.. :-/

For me, no. I did a clean install of El Capitan and it didn't seem super impressive (tho it did clear out years of redundant stuff left over from installation overwrites going back years). But I can't imagine too much would get changed if I did it now. No miraculous snappiness, at least.
 
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fruitpunch.ben

macrumors 6502a
Sep 16, 2008
594
173
Surrey, BC
I don't know why everyone always suggests the USB install disk method to clean install a new OS. It's long, complicated, and requires buying a 16GB USB stick if you don't have one.
There's an easier way, particularly if you only have one computer you want to clean install:

When you boot from the recovery partition it allows you to erase the boot drive and reinstall the last installed version of macOS.

Now, at this stage you probably have El Capitan installed, so you need to download Sierra from the App Store and upgrade as usual. Then once it is installed, restart your computer and hold down command R at restart to boot from recovery partition.
Use disk utility to erase your boot disk then reinstall macOS.

Hope that helps!
 

eeyoredragon

macrumors member
Apr 2, 2005
89
17
I don't know why everyone always suggests the USB install disk method to clean install a new OS. It's long, complicated, and requires buying a 16GB USB stick if you don't have one.
There's an easier way, particularly if you only have one computer you want to clean install:

When you boot from the recovery partition it allows you to erase the boot drive and reinstall the last installed version of macOS.

Now, at this stage you probably have El Capitan installed, so you need to download Sierra from the App Store and upgrade as usual. Then once it is installed, restart your computer and hold down command R at restart to boot from recovery partition.
Use disk utility to erase your boot disk then reinstall macOS.

Hope that helps!
This is typically what I do.

That being said, how is the USB method "long and complicated" compared to doing two installations of the operating system which you do via the recovery partition method?
 

chrisone

macrumors member
Aug 19, 2013
76
27
When you boot from the recovery partition it allows you to erase the boot drive and reinstall the last installed version of macOS.

Can you confirm this? Because on https://support.apple.com/en-us/HT204904, Apple writes that "This installs the OS X that came with your Mac when it was new" and that the new owner (or you) would need to upgrade via the App Store afterwards to get the latest.

Asking because I am not sure which is best as I am planning to give my old iMac away (waiting for the new Pro...)
 
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aj8690

macrumors member
Aug 28, 2012
90
72
Orlando, Florida, USA
I don't know why everyone always suggests the USB install disk method to clean install a new OS. It's long, complicated, and requires buying a 16GB USB stick if you don't have one.
There's an easier way, particularly if you only have one computer you want to clean install:

When you boot from the recovery partition it allows you to erase the boot drive and reinstall the last installed version of macOS.

Now, at this stage you probably have El Capitan installed, so you need to download Sierra from the App Store and upgrade as usual. Then once it is installed, restart your computer and hold down command R at restart to boot from recovery partition.
Use disk utility to erase your boot disk then reinstall macOS.

Hope that helps!
That works but is it really easier though? Upgrade + erase and new installation is typically going to take longer than just erase and restore from installer, in addition to putting a lot of unnecessary wear from upgrading first before doing a fresh install on the flash storage that most of us have.
[doublepost=1474472165][/doublepost]
Can you confirm this? Because on https://support.apple.com/en-us/HT204904, Apple writes that "This installs the OS X that came with your Mac when it was new" and that the new owner (or you) would need to upgrade via the App Store afterwards to get the latest.

Asking because I am not sure which is best as I am planning to give my old iMac away (waiting for the new Pro...)
The local recovery partition does restore the version that you last installed. It's the Internet Recovery that installs the original version that came on your Mac.
 

KALLT

macrumors 603
Sep 23, 2008
5,173
3,215
Can you confirm this? Because on https://support.apple.com/en-us/HT204904, Apple writes that "This installs the OS X that came with your Mac when it was new" and that the new owner (or you) would need to upgrade via the App Store afterwards to get the latest.

Asking because I am not sure which is best as I am planning to give my old iMac away (waiting for the new Pro...)

Internet Recovery (command–option-R) ≠ Recovery (command–R). Recovery uses a local partition on your disk, whereas Internet Recovery loads an environment on-demand. The latter will always load one to install the original version of OS X, whereas the regular Recovery will always load the version that matches its own version.

Is this really worth doing? I have "dirty" upgraded since I got my MBP in 2011 and not noticed any issue so far.. :-/

No, it is not. I have been advocating against it. It is a waste of time for most users and provides no absolute benefits. I only recommend it if system configurations were changed (e.g. in /private/etc or /private/var), because this is something that a reinstallation will not fix reliably (given that it is expressly meant for configuration). Under normal circumstances, the user never changes anything of this manually.

Since El Capitan, Apple claims complete ownership over /System, /bin, /sbin and /usr. This makes it very difficult to even break anything beyond repair. Normally, a reinstallation is enough to fix such problems, because it is effectively an overwrite anyway.
 
Last edited:

edgonzalez32

macrumors 6502a
Jul 21, 2011
536
972
I don't know why everyone always suggests the USB install disk method to clean install a new OS. It's long, complicated, and requires buying a 16GB USB stick if you don't have one.
There's an easier way, particularly if you only have one computer you want to clean install:

When you boot from the recovery partition it allows you to erase the boot drive and reinstall the last installed version of macOS.

Now, at this stage you probably have El Capitan installed, so you need to download Sierra from the App Store and upgrade as usual. Then once it is installed, restart your computer and hold down command R at restart to boot from recovery partition.
Use disk utility to erase your boot disk then reinstall macOS.

Hope that helps!
Because that's two installs you need to sit through.
 

Zanoryt

macrumors newbie
Sep 19, 2012
22
7
Mountain View, CA
I install new OSes from scratch every time, and never do upgrades. This may be seen as a hassle, but my system runs at top speed and I greatly reduce the accumulation of malware, spyware, and all sorts of junk software that I install over time but forget to remove.

In fact, I reinstall at least once every 6 months. But it's not difficult to do! It now takes me no longer than a couple of hours, and most of the process is automated.

I have documented a Gist of my process (now tuned for macOS 10.12 Sierra). I encourage all to fork it and customize it for their own needs and software. This would allow you to more easily set things up so you can be more aggressive about reinstalls.

This will instill a habit of keeping your user data and content stored on a secondary partition/drive and keeping backups, so that you can reinstall the OS without worrying about losing what is important.

Keep in mind that once installed as new, if you keep a backup close by (and you should) you could always import your user profile during the post-install setup wizard (though I don't recommend that).
 
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Crazy Badger

macrumors 65816
Apr 1, 2008
1,213
560
Scotland
Or save yourself a shed load of time and effort and just upgrade!

Really, this should be a last resort type of thing if you're having major problems with the OS and don't know what they are or how to resolve.

I haven't done a clean install for years and all my machines are running perfectly. I'd like to bet they are no slower than a similarly spec'ed machine with a clean install.
 

fastasleep

macrumors 6502
May 21, 2010
408
527
Seattle, WA
If you just go and restore from time machine you defeat the purpose of clean installing. You can do a selective restore, but don't restore your settings.

I was going to say the same thing. Since they suggest Migration Assistant without any details, by default you'd be copying over all the cruft in your Library, Applications, invisible files leftover from old apps, NSA spyware, etc. which totally defeats the point of a clean install. You might as well just upgrade in place if you're going to import your entire user account with Migration Assistant. Of course there are options to only import some parts of your account if you wanted to migrate some aspects of your account and manually reinstall apps for example.

Someone correct me if I'm wrong.

From using Migration Assistant for a decade, I have random hidden files all over the place, old preferences and application support files, all sorts of kexts that may or may not be useful still or even compatible, and who knows what kind of unsecured data that I don't even know about. I think my next MacBook Pro I'll start fresh and manually migrate all my data, as painful of a process that's likely to be, to finally be rid of all the clutter. Maybe rebuild my iTunes Library from scratch too as who knows how corrupted that thing might be.
 
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