I want to upgrade macOS on my father's Mac, as it's quite out of date (currently running Mac OS X 10.6.8). I understand how to back up files before upgrading, but what about apps? For example, he uses Matlab and would want it to remain available after the upgrade.

Would that mean reinstalling it after the upgrade (which I suppose might require him to know the product key, which he might not know: he generally doesn't know such things) or is it somehow possible to transfer one's current apps to the post upgrade system without having to reinstall them?

Here is the specification of the Mac in question:

OS: Mac OS X Version 10.6.8
Processor: 2.3 GHz Intel Core 15
Memory: 4GB 1333 MHz DDR3
Model Name: MacBook Pro
Model Identifier: MacBookPro8,1
No. of processors: 1
No. of cores: 2
  • 1
    Please edit your question to supply the model of Mac your father is using. As mentioned below, the Mac may not be able to run High Sierra.
    – IconDaemon
    Commented Aug 1, 2018 at 14:54
  • From your Mac description, your best upgrade OS target will be Yosemite. Do you have a Yosemite installer app (/Applications/Install OS X Yosemite.app) or an USB to install Yosemite?
    – dan
    Commented Aug 1, 2018 at 16:39
  • @daniel Azuelos Not sure but I think when I tried to install Yosemite a message said that if it can run that it can run Sierra or something, but when I tried to install that it said it needed to have Mac OS X 10.8 first and I couldn't install that which I think was because it said it wasn't available in the UK: not completely sure that was the reason but it wouldn't install it for some reason. No I have no memory stick at the moment. Commented Aug 3, 2018 at 8:03
  • From the information you provided, you can upgrade from Snow Leopard 10.6.8 to Yosemite 10.10.5. See the detailed answer I provided. You can technically upgrade to High Sierra but your MacBook Pro won't be usable, that would be a total waste of time.
    – dan
    Commented Aug 4, 2018 at 7:18

4 Answers 4


Generally, no separate action is required with respect to apps when upgrading macOS. All the installed apps and user data continue to remain available post upgradation.

However, it's important to ensure that the apps are compatible with the upgraded version of macOS before actually performing the upgrade. This information can generally be obtained from the vendor/developer of the app.

There may be cases when upgrading macOS will also require you to upgrade the version of the app and associated licensing costs (if any). These all questions could be rightly addressed by the app vendor/developer.

On an important note, Apple advises to perform a system backup to guard against rare circumstances, where the upgrade goes wrong.

In your specific case, consider checking what's the latest version of OS X/macOS the machine can run. It might not go all the way to macOS High Sierra if it's too old. Obtain that information and plan your app update strategy accordingly.

Also, you should consider testing restoring your system from the backup to ensure its trustworthiness. People really don't want a backup - they want to know they can restore and the restore works. The backup is just the preparation to do the restore. You can run an erase/install and just reinstall the current OS to test things without the new OS potentially breaking things. That way you know you can restore the current OS first before you even think of upgrading.

It is worth emphasizing the should test since Mac OS X 10.6 Snow Leopard is really a long way back and it's very likely many of the apps will fail on macOS Sierra 10.12 or later and need license keys, upgrades, etc. Having a bootable backup or clone might even be worth the effort. You are about to break lots of things and gambling that they are all minor or not used since tons of functions and features from 10.6 are changed/deprecated/turned-off now. Any one upgrade alone, generally is easier to risk without a test run, but this is decade of neglect in terms of keeping things moving on the routine update/upgrade chain.

  • For a bootable backup, use CarbonCopyCloner. It has a fully functional free trial so you won’t even need to pay for the one use.
    – Wildcard
    Commented Aug 1, 2018 at 15:14
  • @WIldcard Yes I noticed this. Commented Aug 3, 2018 at 8:00

Here's how I do this.

  • Get a USB drive at least the size of your internal hard drive.
  • clone your hard drive onto the USB drive (using whatever method you prefer, I use disk utility), and give the external drive a different name (e.g. MyHD_CLONE). Again, option-reboot into that hard drive. Set it as the default boot drive. Now you have your exact same environment, except it's a clone. Don't save work here.
  • Check that all your applications work. Some may dislike being moved onto a different drive with different serial number and name, and have already failed. You can't test those here unless you have the keys.
  • Now install the OS X update on the clone. Take special care at the drive selection screens not to clobber your internal hard drive, which it may default to.
  • Once the OS X update finishes, go to Apple/App Store and install all relevant updates. Many of your apps will have updates simply because they are on a newer OS After that finishes, give it one more go-around, as some updates are dependent on other updates. (more on Windows than Mac, but still).
  • Now give your applications a thorough test.

If an application does not work, it's either because of a licensing issue (the DRM didn't like that you updated OS and wants you to authenticate again), some glitch which arose due to accumulated clutter lying around your system, or the app simply can't work on this OS. A cold-install will distinguish the latter case from the others.

Once you've "dialed everything in" on the test or clone drives, you can install on the main drive with confidence.


To answer your question (everyone is asking oneself before an upgrade): which applications the update to MacOS X will break?

There is no professional, nor any easy answer to this question (this isn't typical of MacOS X, it is nearly the same situation on any OS):

  • Apple doesn't provide a database of known incompatabilities,

  • most application developpers don't provide a database of known incompatibilities.

Hence it is up to the user to take this risk and test by himself.

Here is my personnal advice on how to proceed starting from a Mac running Snow Leopard.

  1. Use an external disk (rather a new one) and make a clone copy of your actual internal disk on it. For this task use Carbon Copy Cloner 3.5.7 (which is the last one compatible with Snow Leopard).
  2. Download Yosemite combo update.
  3. Install it on your external disk.
  4. Boot from your external disk now running Yosemite 10.10.5.
  5. For each application important for your father to work,

    check if it is running correctly

    if it doesn't, find if the application editor provides a compatibility support (as Carbon Copy Cloner does professionnaly) and download the appropriate update. Beware, in some cases this search for the compatible version will be a failure. This is the reason why some editors don't like to advertise this compatibility matrix and let the user discover it on his own.

    continue with next application.

If you follow this receipe, your original disk is still hosting Snow Leopard. It is a de facto backup you can schwitch back to as quickly as switching the boot disk (~5 minutes).

  1. Run on your external disk hosting Yosemite and its set of applications (kept as is or updated or abandonned) for a few days (I advise to check it for a week) with all these applications, to detect all the other possible incompatibilities.
  2. If the state reached is OK, do the reverse of step 1.: clone your external disk onto your internal one, and switch on it as the boot disk.

Will it work, yes, though all the caveats apply.

I agree, you should have a bootable back up ready and handy, especially since 10.6 is where Carbon apps will start breaking. Hence why some people sometimes keep a 10.6.8 installation/virtual machine handy.

10.7 is when they removed that and so -- every app based on that will fail to run.

If they were using the more OSX framework, then the will probably run -- maybe, it'd depend on the app...I can't say yes or no...and in some cases, you might just want to upgrade on principle, just to gain any improvements.

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