1. Upgrade From Lion To Mojave
2. Upgrade Mountain Lion To Mojave
3. Upgrade From Mountain Lion To Mojave
4. Upgrade From Lion To Mojave
5. Updating From Lion To Mojave

1. Not sure why the OS upgrade from Sierra to Mojave would have de-selected these options but there you go. Improve this answer. Mobile Account on Lion 10.7.4.
2. MacOS Mojave 10.14 can upgrade High Sierra, Sierra, El Capitan, Yosemite, Mavericks or Mountain Lion macOS High Sierra 10.13 can upgrade Sierra, El Capitan, Yosemite, Mavericks or Mountain Lion Safari downloads the following older installers as a disk image named InstallOS.dmg or InstallMacOSX.dmg.
3. Upgrading from macOS Catalina 10.15 or Mojave 10.14? Go to Software Update in System Preferences to find macOS Big Sur. Click Upgrade Now and follow the onscreen instructions. Upgrading from an older version of macOS? If you’re running any release from macOS 10.13 to 10.9, you can upgrade to macOS Big Sur from the App Store.

macOS Big Sur elevates the most advanced desktop operating system in the world to a new level of power and beauty. Experience Mac to the fullest with a refined new design. Enjoy the biggest Safari update ever. Discover new features for Maps and Messages. And get even more transparency around your privacy.

Check compatibility

The macOS Mojave was the fifteenth release from Apple for their macOS family and was made available to the public on the 24th of September in 2018. The macOS Mojave 10.14.1 (the updated version) was released on the 30th of October of the same year with a couple of new updates. Mojave is the next update to the Mac operating system High Sierra. It had been released on 24th of, September 2018 as a free update that is available for those who want to install and try this all-embracing OS. An attractive upgrade with dozens of latest preferences for handling documents, applications, and media files.

macOS Big Sur is compatible with these computers:

Upgrade From Lion To Mojave

MacBook introduced in 2015 or later
MacBook Air introduced in 2013 or later
MacBook Pro introduced in late 2013 or later
Mac mini introduced in 2014 or later
iMac introduced in 2014 or later
iMac Pro
Mac Pro introduced in 2013 or later
View the complete list of compatible computers.

If upgrading from macOS Sierra or later, macOS Big Sur requires 35.5GB of available storage to upgrade. If upgrading from an earlier release, macOS Big Sur requires up to 44.5GB of available storage. To upgrade from OS X Mountain Lion, first upgrade to OS X El Capitan, then upgrade to macOS Big Sur.

Make a backup

Before installing any upgrade, 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.

Get connected

It takes time to download and install macOS, so make sure that you have a reliable Internet connection. If you're using a Mac notebook computer, plug it into AC power.

Download macOS Big Sur

If you're using macOS Mojave or later, get macOS Big Sur via Software Update: Choose Apple menu  > System Preferences, then click Software Update.

Or use this link to open the macOS Big Sur page on the App Store: Get macOS Big Sur. Then click the Get button or iCloud download icon.

Begin installation

After downloading, the installer opens automatically.

Upgrade Mountain Lion To Mojave

Click Continue and follow the onscreen instructions. You might find it easiest to begin installation in the evening so that it can complete 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.

Allow installation to complete

Please allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart, show a progress bar, or show a blank screen several times as it installs both macOS and related updates to your Mac firmware.

Stay up to date

Upgrade From Mountain Lion To Mojave

After installing macOS Big Sur, you will be notified when updates to macOS Big Sur are available. You can also use Software Update to check for updates: Choose Apple menu  > System Preferences, then click Software Update.

Upgrade From Lion To Mojave

Or get macOS Big Sur automatically

Updating From Lion To Mojave

If you're using OS X El Capitan v10.11.5 or later and your App Store preferences or Software Update preferences are set to download new updates when available, macOS Big Sur will download conveniently in the background, making it even easier to upgrade. A notification will inform you when macOS Big Sur is ready to be installed. Click Install to get started, or dismiss the notification to install later. When you're ready to install, just open the file named Install macOS Big Sur from your Applications folder.

Learn more

• If the installer shows a list of apps that are not optimized for your Mac, learn about 32-bit app compatibility, then choose whether to proceed with the installation.
• For the strongest security and latest features, upgrade to macOS Big Sur. If you have hardware or software that isn't compatible with Big Sur, you might be able to install an earlier macOS.
• You can also 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.