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How often do you clean install macOS?

ProQuiz

ProQuiz

macrumors 6502
Original poster
Jul 15, 2009
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I have a MacBook Pro 14" with the M3 Pro chip. It came with Sonoma installed. I updated to Sequoia when it was released. I am thinking I should do a clean install once macOS 15.2 is out (and the bugs in 15.1 are hopefully squashed).

Is it worth doing a clean install when new macOS versions (not incremental but, for example, from macOS 14 to macOS 15) are released?
 
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There is no advantage whatsoever to doing a clean install. If you have any desire to do so you are wasting your time. Every MacBook Pro like yours has the same system files, bit for bit. The system is read only, signed, and verified before every boot. If even one bit differs, the machine won't boot.

If you are concerned about non system stuff, you can restore to factory settings under System Settings > General > Transfer or Reset > Erase All Content and Settings. Then reinstall everything from scratch.

Read this for full information:

eclecticlight.co

How to ‘clean’ install modern macOS

If you normally ‘clean’ install a new version of macOS, how can or should you do that with Sonoma or another recent version on a modern Mac?
eclecticlight.co eclecticlight.co
 
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I do it once per year, when inst a new major version of macOS, on my old Intel Mac.

But now with my new Apple Silicon Mac, I really don’t know how a clean install is made. So I guess I’ll keep updating it for the time being.
 
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I never have. That includes the annual upgrades and countless updates and migrating from 1 Mac to another a few times over the years...from the very first Intel Macbook Pro I had OSX Leopard up to today with Sequoia.
 
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I have once or twice in the last 17+ years. But mostly when I buy a new Mac (every 5-6 years) I almost always do a migration from my old Mac, though there are times when I set it up from scratch. Then I continue to upgrade over that machine until I am ready to buy a new one.
 
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Is cleaning installing macOS 15.1 and then updating to 15.2 the same as clean installing macOS 15.2? I've been told that every macOS/iOS update is treated and done as a "clean install" (at least the OS partition). So there would be no leftover OS files or remnants from the older version when updating to the newer version?
 
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ProQuiz said:
Is cleaning installing macOS 15.1 and then updating to 15.2 the same as clean installing macOS 15.2? I've been told that every macOS/iOS update is treated and done as a "clean install" (at least the OS partition). So there would be no leftover OS files or remnants from the older version when updating to the newer version?
Click to expand...
I’m also interested in knowing this.
 
ProQuiz said:
Is cleaning installing macOS 15.1 and then updating to 15.2 the same as clean installing macOS 15.2? I've been told that every macOS/iOS update is treated and done as a "clean install" (at least the OS partition). So there would be no leftover OS files or remnants from the older version when updating to the newer version?
Click to expand...
This is correct. As stated in post #4, every Mac running the same macOS version has exactly the same files. They are bit for bit identical.
 
My current Mac is a little over four years old and is still on its factory install. The only time I've actually needed to do a clean install was the 2003 Power Mac G4, which had a broken factory install if you bought it after a certain date.
 
You can do a refresh if you’re experiencing some weirdness - my 2019 16” I did it to about 18 months ago and it was more stable - but it really won’t do as much as it did back in the Windows days.

(also the real culprit on that machine seems to be the SMC getting borked every 3-4 months rather than the OS itself)
 
It's just a waste of time. macOS isn't like Windows which always tended to corrupt itself or become slow over time lol. Although I haven't used Windows in years so maybe they've fixed that too.

You're just gonna be spending a significant amount of time to setup everything again once you do a clean install.
 
Usually with each major OS release. I know it doesn't need it, and I really could use the time for something else, and it is probably more a mental struggle with mine that affects even other areas of life… but there's something about a clean install and setting everything back up (and seeing how long I can go keeping everything as default as possible). It sounds stressful, but it's like someone in the backyard shop working on a car or woodwork, I like tinkering with it since it is the only hobby I have.
 
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For my daily Mac's, never. I survived the 90's trauma of keeping Windows running, so once I went Mac for my personal life I never went back. I've only done two clean installs: when tinkering with an old Mini (Now that I'm old I can admit that I failed at trying to install, let alone learn and understand, an alternate OS to repurpose it as a media server) or when I had wiped a swollen MacBook for recycling and, for a reason I don't remember, needed to reinstall the OS on it temporarily.
 
When I upgraded my MPro 3,1 from a HDD to a SSD, never ever since with multiple MacBooks, iMac, Mac Studio
 
tonywalker23 said:
Usually with each major OS release. I know it doesn't need it, and I really could use the time for something else, and it is probably more a mental struggle with mine that affects even other areas of life… but there's something about a clean install and setting everything back up (and seeing how long I can go keeping everything as default as possible). It sounds stressful, but it's like someone in the backyard shop working on a car or woodwork, I like tinkering with it since it is the only hobby I have.
Click to expand...
Same.

But now on Apple Silicon Macs I don’t know if the procedure of booting from a pendrive still works or not…
 
Anyone else old enough to remember installing an OS from floppy disk?

Sitting there for hours, ok it's finished with this disk, remove the little 3.5" thing, insert disk 37 of 64, hearing the click and the whir as it spooled up and oh no, disk 37 is corrupt. Game over.

Sh*t is so easy these days, if I hear a younger coworker complain about their phone or computer I think to myself "bub.. you have NOOO idea .."
 
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chabig said:
There is no advantage whatsoever to doing a clean install.
Click to expand...

Well, there are some advantages, but they're probably not the advantages that people are seeking. I've probably still got a few OS9 support files hidden in my file system. Mostly anything from that far back is small in size and harmless, but that's not always the case. Every now and then I use something like OmniDiskSweeper to browse my system folders for kruft that shouldn't be around anymore. I have cleaned out many GBs of junk that I had no idea was even there!
 
Apple_Robert said:
If the SSD on a M series Mac dies, the Mac will not boot, regardless of any working external drive connected.
Click to expand...
No no, I mean the classic procedure to clean install an Intel Mac booting up with an installation pen drive (made using the system command CreateInstallMedia) connected while pressing the option key… then booting from that pendrive, selecting Disk Utilities, erasing the internal drive, and installing the new system, all from the pen drive. All while the SSD works, of course.
 
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