• You don’t mention a firmware update being required to install Mojave. Mid 2010 Mac Pro running 10.13.6. What is the nature of the FW update and why is it needed? Yes, I know about video card reqmt. Already have that.

  • this has never happened before-the installer do not want to install the system on my original start up disk.I have iMac 5K ,late 2014. What might be wrong?

  • If you don’t do a clean install, run First Aid on the dis k you are going to install on first. This will save a lot of hassle if there is a problem that could cause the install to fail. (My lesson learned from High Sierra).

    I had no problems with Mojave other than the time took. I started at 10 PM and finished at 2 AM. (My wife wasn’t happy about that, but then she doesn’t like me rebooting when she is using the Apple TV.)

    Only surprise was it converted my hard drive into an APFS Volume. I heard a lot of talk about that not happening with High Sierra and no mention of it leading up to Mojave, that it took me by surprise to see the change the first time I opened Disk Utility.

  • If I opt for a clean install to avoid legacy detritus, will Time Machine still recognise my ‘new’ hard drive and system?

  • If I do a clean install, will Migration Assistant move my applications as well as my data? I’m concerned because, in past updates, Microsoft told me I had used my office Activation Code before and I had to purchase a new copy of Office if I wanted to activate it.

  • I came for expert advice on choosing to upgrade vs. clean install, but instead this was a “how to” for both.

  • The v2.3.15.1067 firmware update, available on the OWC web site, resolved the issue of the 10.14 Mojave installer reporting that it could not install on my “third-party” storage. My first re-installation re-attempt went off with a hitch, and operation is smooth and flawless now.

  • The article doesn’t attempt to advise, let alone answer the question posted in the headline; it only outlines the steps for either choice; so I assume it is instead attempting to invite discussion on the subject, n’est-ce pas ?

    I always laugh and shake my head every year listening to the pundits (most of whom came from Windows) discuss how they do a wipe and reinstall every year and/or with every new Mac, as though the hours and hours, if not days of reconfiguring and reauthorizing all your software and restoring all your preferences and third party tricks and tools and homemade services, scripts, etc., is somehow a magical curative to problems that never existed. Were you having troubles with your current install? No? Then why are you blowing away that foundation?

    As I type this on my current machine, I am sitting on top of a single-threaded-life install that has merely been upgraded, release to release, years after years, now year after year, since the days of the first Mac OS X 10.1 Cheetah release in 2001 — and I just can’t recall with certainty, but my fading memory says I took it all the way from the public beta.

    Further, it has simply migrated from Mac to Mac over the years, and it has even forked itself onto multiple Macs running to this day. And we pulled our old Mac OS Classic systems over from old Mac OS 9 System Folders over the network with AFS.

    Looking in my preferences and Library folder, I have objects with creation dates from 2004; and I’m sure there are objects still onboard older than that; I know I used to blow out prefs and libraries during troubleshooting (back when I was coerced to run Adobe and MS products that always misbehaved), and usually I merged the originals back in after identifying the bad object(s), but apparently in 2004 I was lazy or determined it wasn’t worth preserving; or everything prior had at one point or another required replacing.

    Do I have 17 years of cruft on board? Sure. But who cares? It’s *NIX; nothing is called or loaded unless told to do so; it’s nothing but a few MB, maybe even a few or several GB, if I were to spend hours and days sorting and cleaning said cruft and keeping a tally. If I were stuck on a MacBook Air with a tiny hard drive, I might worry about it. Hard drives are cheap. SSDs have been plummeting in price the past few months ( I paid $325 each for four 1TB EVOs not more than a year ago, and was thrilled I got them at that price; today, I can get the newer version for $175 or less).

    Will I do some cleanup as 32bit apps are completely deprecated in 2019? Probably; but I still have Carbon apps and components I haven’t bothered to delete, so there’s a chance my desire to just do work *with* my computer, not *on* it, will prevail.

    And, this is true not only for me, but for the fleets of employees and Macs that have stuck around over the years; we never clean wipe until its time to sell; then it’s a clone, carried to the new Mac, which is overwritten with the old Mac’s clone. (the only times this has been a problem is with day zero Macs whose OS is newer than what is available to the public; so the merging/migrating is a bit more complicated; but we’ve never once bothered with rebuilding from scratch).

    And, for those already typing a rebuttal, yes, I have, with pretty much every mature OS version, done benchmarks against a virgin, pristine installation; there has never been a repeatable, let alone appreciable difference in performance.

    If you don’t have much third party software, or your own customizations, and a clean install is worth your time to give you some piece of mind, go for it; but you’re running macOS and not Windows for good reason; if there are installed items causing your troubles now, just remove them; it’s not like you’ve got a registry or .dll dependencies or anything remotely similar. The only troublemakers used to be Adobe and MS, and a couple others that married licensing to a specific Mac by serial number, or even did nasty stuff by writing licensing info to the hidden volume structure maps on a particular hard drive. If you’re just upgrading an existing Mac, even that isn’t an issue.

    Do upgrades occasionally bork? Yup? But so do point-release updates, and we’ve always been content to just re-run the latest combo updater, or restore from clone and try again.

    Again, it’s *NIX; you don’t have to freak out about dependencies; if a library or kext or plist is corrupt, just overwrite it and live your life.

    So, which is right for you? I say, with nearly two decades of experience, it’s 98% likely you should just upgrade; but maybe wait a few weeks until you hear there are no major issues, if any words in this article made your eyes glaze over.



    • If there was a like button, I would have clicked on it!

    • I’ll second what Frederico is suggesting, just upgrade and please don’t forget: it is a well organized NIX.

      All the best,

    • Frederico, makes good sense yr suggestion. Last couple in-version updates I have downlded the combo update file. Question – Since this is a major version upgrade, if I do just the upgrade (not fresh install), does it help/would you recommend to do combo file update on first Mojave update? Am not expert with all the ins & outs so hope it is a sensible question. Thanks

  • Thanks Tom, but neither works because I get “Cannot install to third party storage” error. I have Aura as my main SSD. I used a third party external SSD for my clone. Neither is seen as an Apple disk. Failure.