How to keep 32-bit apps working in Catalina?

Thinking of buying a new iMac which comes with Catalina. I don’t want to lose all my 32 bit software. Why can’t I install a bootable version of Sierra on an external disk, boot from that disk and continue to use this software.

Or you could use virtualization software.

VMware Fusion 12 is now even free for personal use.


Will the new iMacs boot Sierra? I kind of doubt it. Maybe Mojave, but Sierra’s pretty old, and even if Mojave booted, I don’t think I’d want to rely on it working completely and continuing to work. Virtualization is the way to go IMO.

No, a new iMac will not boot Sierra. At best you’ll be able to boot Catalina. If you need anything older you’ll have to do it from within a VM.

Has anyone here tried doing this with VirtualBox?

Also, does the guest version of macOS have to be a version compatible with the native hardware (that is, a version that it could boot natively)?

I ask because I need to do the same thing - set up a VM for some of my old 32-bit apps. I have an installer DVD for Mac OS X 10.5, which I would actually like to use because it includes Rosetta and would therefore be able to run my even older PowerPC apps.

Or is that going to be more trouble than it’s worth?

I have not done this on VirtualBox, but I have set up a working VM for Lion 10.7 in Parallels on a 2015 MBA. So at least using Parallels you can set up a working VM for a non-supported older version.

Hi Adam - where is it noted that Fusion is free for personal use? I am only seeing payment options.


On the main Fusion product page, there’s a box that reads:


Ah thanks! I went right to the version 12 page and didn’t see it. I will check it out.


There are several specs you need to know for virtual machine software:

the hardware required to run the VM host version (fusion 11.5, parallels 15, etc), or conversely, which VM host version/s will run on your hardware.

the OS versions needed to run a VM host version

the OS versions allowed as clients for a particular host version

So on my Sierra iMac (2017), I can run up to version 11.1 of Fusion, which will let me run from snow leopard server through catalina as client systems (plus assorted windows and linuxes). In general, the host can run many older client versions, and maybe a few OS versions newer than the host OS.

For VMWare Fusion you get to hunt a bit in the help to find this for older versions. Parallels has a one page spec sheet for the most recent few versions. I don’t know off hand about VirtualBox.

For Snow Leopard, only the server version will install readily due to license issues. Regular SL needs a small hack to change a file name in the installer. Seek and you shall find.

You won’t be able to run PPC Tiger, and it requires a fair bit of hacking to run intel Tiger or Leopard, because they aren’t supported. For PPC virtual systems, look into the vMac and Sheepshaver emulators, or keep an eye out for old hardware. I love the luxo lamp imac that a friend found for me at goodwill for $10, no repairs needed. It’s running PPC Tiger + Classic mode. Old laptops can work well too, aside from the dead batteries. You generally need to keep them plugged in while using them. I haven’t found any reliable source for replacement batteries.

I’d suggest the free home use Fusion over VirtualBox if you don’t plan on commercial use, and if your current mac can support version 12. Less fuss, better features.

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Thanks for the effort. I had no idea. Life is getting a lot more complicated. Feel like I’m having to deal with a windows box.

Yes, VitualBox can do this, only caveat is that the Sierra installer has a bug making it unusable. See the VirtualBox user fora. I was finally able to copy an installed Sierra volume in a High Sierra VM using CCC. For High Sierra, Catalina, Snow Leopard, El Cap and Yosemite you can use the regular installers. I’m running the VM’s on a Mac mini that came with Sierra, so older OSses are possible.

I know what you’re saying! Last night I setup a new external to put VMs on for software. I downloaded a trial of Parallels which was easy to set up. But dealing with the expired certificates on the OS installers, and even trying to find full installers as opposed to updates, was quite the pain. So far I managed Sierra (which I didn’t need but figured I could then update it) and Mojave.

Mojave ended up being the easiest as I downloaded it from the new install without being logged in, so it didn’t ding me as already having gotten it.

I set up a VM a couple of years ago to run old apps on a different machine (Eudora and Quicken), and as Gastrop said, you need the server version of Snow Leopard to do that. I also had to buy the CD specific to that machine off eBay as the person I got it from didn’t have any of their original disks. For that project I used VirtualBox, and going from memory of 2 years ago, Parallels was easier to work with.

Now I’m working with my 2015 MBPr so no CD. Definitely doable but a bit more difficult.


Adam made an article that has all the links:

Thanks! I can’t believe last nights googling didn’t bring that one up! It’s not like I don’t hit the Tidbits page regularly….


I have an iMac 2017, MacPro 2012, MacBook Air 2015-
I can boot up from other internal volumes (max Mojave) on the Mac Pro. External drives including Big Sur on the iMac and I assume the same from the Mac Air. So basically If I need a 32 bit app- it is accessible and if I need Mojave for Turbotax -that is also accessible from an external drive. (But I have partitioned the iMac with Mojave and have 2 volumes on the internal with 2 Mac OS systems).
So I guess all this discussion of virtual use with VM or Parallels is if your Mac can not boot into Mojave or below and you need the 32 bit apps, correct? I have Parallels on my iMac using Windows- But if I want a virtual machine to boot into Catalina or above - how do I go about this? That basically is my question- Please direct me to a link to accomplish this. Do I need to erase the windows partition? Or can I have both windows and a Mac OS?
Oh and Thanks

So…I’ve downloaded and gotten a license for Fusion 12 Player…but I tried to import my Mojave Parallels 2 or so versions back image to no avail. I can muck around with this until I figure it out…or I can ask and I’m easy. What do I need to do to create a new Fusion Mojave VM…build myself a Mojave bootable Installer USB drive or make an ISO or what?

For my limited usage to use some old 32 bit only apps…paying Parallels 50 bucks a year seems foolish…but in the interest of efficiency figuring out how to install Mojave under Fusion 12 Player…it’s better to ask.

This is a handy discussion! But am I the only person who wishes we could use numbers to refer to OS versions, instead of the silly names? I cannot remember which name goes with which version so I constantly have to look it up. The whole practice of giving operating systems cute names is… cute, but not actually helpful. Is my Android phone running Lollipop, Tootsie-roll, or SweetTart? Which is newer? Sorry, here’s a case where Windows is better–at least you know what version you’re using!

Apple Menu > About This Mac will show both name and version number. I usually use that to remind myself that Catalina is 10.15 and then count backwards from there. Obviously, you still need to know the name order: Mojave, HS, Sierra, El Cap (always forget that one), Yosemite, Mavericks, and then the cats starting with ML.

With Big Sur this should all become easier since 10.16 -> 11. And I expect we’ll see that increment annually with the major releases as we’ve grown accustomed to on iOS.

Yes, as you say, I can look at what I’m running, but then I have to remember what comes before and after. And that’s my point: Numbers have a sequence, names do not. They’re fun but unhelpful.