To get the latest features and maintain the security, stability, compatibility and performance of your Mac, it's important to keep your software up to date. Apple recommends that you always use the latest macOS that is compatible with your Mac.
The older macOS High Sierra had a little more scope. Apple said that would run happily on a late 2009 or later MacBook or iMac, or a 2010 or later MacBook Air, MacBook Pro, Mac mini or Mac Pro. It takes time to download and install macOS, so make sure that you're plugged into AC power and have a reliable internet connection. These installers from the App Store open automatically after you download them: macOS Catalina 10.15 can upgrade Mojave, High Sierra, Sierra, El Capitan, Yosemite, Mavericks.
Learn how to upgrade to macOS Big Sur, the latest version of macOS.
If a macOS installer can't be used on your Mac, the installer will let you know. For example, it might state that your Mac doesn't have enough free storage space for the installation or that the installer is too old to be opened on this version of macOS.
If you want to check compatibility before downloading the installer, learn about the minimum requirements for macOS Catalina, Mojave, High Sierra, Sierra, El Capitan or Yosemite. You can also check compatible operating systems on the product-ID page for MacBook Pro, MacBook Air, MacBook, iMac, Mac mini or Mac Pro.
Before installing, it’s a good idea to back up your Mac. Time Machine makes it simple and other backup methods are also available. Learn how to back up your Mac.
It takes time to download and install macOS, so make sure you're plugged into AC power and have a reliable internet connection.
These installers from the App Store open automatically after they've been downloaded:
Your web browser will download the following older installers as a disk image named InstallOS.dmg or InstallMacOSX.dmg. Open the disk image, then open the .pkg installer inside the disk image. It will install an app named Install [Version Name]. Open that app from your Applications folder to start installing the operating system.
Follow the onscreen instructions in the installer. It might be easiest to start the installation in the evening so that it can be completed overnight, if needed.
If the installer asks for permission to install a helper tool, enter the administrator name and password that you use to log in to your Mac, then click Add Helper.
Please allow the installation to be completed without putting your Mac to sleep or closing its lid. Your Mac may restart, display a progress bar or show a blank screen several times as it installs both macOS and related updates to your Mac firmware.
You might also be able to use use macOS Recovery to reinstall the macOS you're using now, upgrade to the latest compatible macOS or install the macOS that came with your Mac.
One of my computer repair customers brought in a MACBook Pro model A1278 2011 with a non functioning operating system. I decided to perform a MAC Lion Upgrade to High Sierra, after backing up their important data of course. First thing you want to do is boot into Apple’s recover menu.
I choose to use the command plus R keystrokes. You want to hold down both these keys after your Macintosh powers on and you hear Apple’s proverbial chime. You must have an Internet connection to perform a Macintosh operating system installation this way.
You can even connect to a WiFi Internet connection. Eventually, after downloading some files you will see a MAC OS X Utilities screen. Now you want to choose “Disk Utility”. Once in disk utility highlight and select the hard drive to install to.
Many times this hard drive is labeled “Macintosh HD”. Click on an “Erase” tab, then click on “Erase” again. You will be prompted to click “Erase” or cancel. This process should only take a few seconds.
Now you may need to “Journal” this file system which is another word for format. You will get prompted to format or journal this drive when you go to install the Macintosh operating system. If the journal tab is green you can go ahead and click on that to format or journal this drive.
You can close and exit disk utility. Now you want to look for “Reinstall MACos” or something similar in MAC OS X Utilities screen. Click on that menu item to begin installing Lion or MACos 10.7.
In the “MAC OS X Lion” screen you want to choose the “Macintosh HD” or whatever you named your erased drive to. Click on “Install”. You should see a progress bar showing you that files are now downloading.
Eventually, this install should complete and your Macintosh Pro will restart. You will be prompted with a registration screen. You do not need to fill this out.
You can leave this form empty and continue on. You will be presented with a “Create Your Computer Account” form. You do NOT have to enter in a password.
Also, you can enable automatic login if you want. Now you will be asked to set your timezone. Next is a calibrate your touchpad screen.
During this configuration process you will be presented with screens asking you to take a picture or select a picture. Finally, MACos Lion 10.7 should take you to your desktop graphical user interface. Before you begin your MAC Lion upgrade to High Sierra, you want to go into software updates either via Apple menu or Apple Store.
You need to go ahead and install any and all updates available. Software updates will require that you restart your Macintosh. Once all updates are installed and you see “No updates are available”, then you can proceed to next step.
I was not able to perform a MAC Lion upgrade directly to High Sierra 10.13. I had to download and install MAC OS El Capitan 10.11 first. You can login to your Apple ID via the App Store application on your MAC and go to “Purchases” or to download El Capitan.
If you have never purchased or downloaded El Capitan before then you will not see it available in “Purchases”. Look for any other MACintosh operating systems that you either purchased or downloaded. My point is that you cannot upgrade directly to High Sierra 10.13 from Lion 10.7.
If you are stuck and cannot upgrade to a newer release of MAC operating system then you will probably need to purchase a newer version.