I have just upgraded to macOS 10.15 Catalina, but I just found out that I still have an old iPhoto database somewhere that I want to integrate with Photos.app using the official Apple iPhoto Updater application. But that’s 32-bit software, so it won’t run in macOS 10.15 Catalina…
What can I do ?
The easiest option is to find a Mac that still runs one of the latest versions of the 32-bit supporting versions of macOS like 10.13 High_Sierra or 10.14 Mojave.
In any version of macOS before 10.15 Catalina, the easiest alternative would probably have been to create a bootable external USB drive running an older version of macOS (like 10.14 Mojave), but by installing 10.15 Catalina you have also installed some drastic security which prevents your Mac from booting from an external drive easily…
So your best option at this moment is to create a virtual machine on your Mac (hoping you have enough internal disk space available – even though you might be able to pull the trick with 16GB free memory, you should be better off with at least 32GB of free memory before you try this).
First, get yourself an official copy of the macOS 10.14 Mojave installer :
- search online for the official macOS 10.14 Mojave installer on iTunes / the App Store, or use this link to download : https://apps.apple.com/sk/app/macos-mojave/id1398502828?mt=12
- the AppStore.app will now automatically open on your Mac on the right page
- click the GET button
- now System Preference’s Software Update window will open with a pulldown window asking you if you are sure you want to download macOS Mojave (since you are running from macOS Catalina even macOS knows that normally doesn’t make sense) click the Download button
- when the installer has been downloaded completely, it will automatically run – however, since your Mac is already running a newer version of macOS (you are running macOS 10.15 Catalina) you will get an error window saying ‘this copy of the “Install macOS” application is too old to be opened on this version of macOS’ so you will only be able to click the Quit button
- then open a Finder window to check where the Install macOS Mojave application is located (it should be located in the Applications folder)
Secondly, get yourself a Virtual Machine application. I would suggest to use Oracle’s VirtualBox, as it’s FREE and the features are nearly identical to commercial Virtual Machine applications like Parallels Desktop or VMware Fusion :
- go to https://www.virtualbox.org and download VirtualBox
- since you are ultimately trying to run 32-bit software, you might be tempted to download VirtualBox 5.2 which is the last version to run on 32-bit hosts ; there is nothing against doing so, but VirtualBox 6 should do great as well, since your Mac is capable of running macOS 10.15 Catalina ; it’s just the VM you’re trying to install (Mojave) that needs to be 32-bit capable, not the host (your Mac running Catalina)
- install VirtualBox
- run Virtual Box
Then, install macOS 10.14 Mojave within VirtualBox. There are various guides available on doing so, but the best way is using the guide created by TobiWasHere! on installing a macOS 10.13 High_Sierra VM, which is (nearly) identical :
When done, run the macOS 10.15 Mojave VM. Then import the 32-bit application into it and run it.
As mentioned before, it’s far faster and easier to borrow a Mac that hasn’t been upgraded to macOS 10.15 Catalina if you incidentally need to run 32-bit software. And if you need to run a 32-bit application for daily use a Virtual Machine is not recommended (even though it can be done), in that case it is probably best to either use a ‘two Mac strategy’ with one running macOS 10.14 Mojave and one running macOS 10.15 Catalina, or – if you insist on using one Mac only – to run macOS 10.14 Mojave only until all applications you need have been upgraded to (or replaced by) 64-bit versions.
Good Luck !