Reinstall Macos Mojave From Catalina

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Downgrade Catalina to Mojave

  1. Rarely, you may need to reinstall macOS Mojave system software, usually for troubleshooting purposes. Reinstalling MacOS Mojave as discussed here will aim to only reinstall the macOS Mojave system software itself, it will not erase the drive, nor will it remove any user data or user files, making it ideal for troubleshooting.
  2. To go back to Mojave from Catalina, you have to uninstall your current version of macOS first. Here’s how to do it: Start booting up your Mac Press and hold Command (⌘) + R once you see the Apple logo.

With macOS Catalina, Apple has completely dropped support for 32-bit apps. Here’s how to see if the apps you have currently installed on Mojave will work on Catalina: Check 32-Bit Apps For Compatibility With macOS Catalina, Here’s How. How To do A Clean Install Of macOS 10.15 Catalina. Applies To: macOS Big Sur, macOS Catalina, macOS Mojave, macOS High Sierra, macOS Sierra, or earlier Mac operating systems. The need to update or reinstall your macOS always follow the release of a new operating system, the slow performance of your Mac, or a system crash. When it comes to reinstalling macOS, users biggest concern is losing data. In testing I've found it doesn't seem to matter what OS the device shipped with, just that you will need to get into a recovery boot session of the macOS version you want to install (or earlier). Devices that shipped with Mojave and have upgraded to Catalina cannot be wiped and reloaded from the Catalina recovery.

If you’ve installed macOS Catalina and run into problems with some of your apps, or you’ve just decided that you don’t like it as much as Mojave, the good news is that you can downgrade back to the previous version of macOS. The bad news is that it’s a lengthy process with several steps. Read on to find out how to do it.

1. Back up your Mac

You should have backed up your Mac before you upgraded to Catalina, as you should before you perform any major upgrade or make any significant change to your Mac. However, the files you’ve been working on since you upgraded won’t be up to date on that backup. So, you should copy those files to an external disk, or a cloud storage service like Dropbox or iCloud Drive so you can retrieve them easily when you downgrade. We’re going to completely erase your Mac’s startup disk, so it’s important to copy anything you need now.

Before you backup, however, you should take steps to remove the junk and clutter from your Mac. There’s no point in backing up all the clutter along with the files you really need. To do that, I recommend CleanMyMac X. It’s the easiest way to clear out the clutter on your Mac. Here are just a few things it can do:

  • Delete years worth of system junk
  • Find hidden apps and folders
  • Neutralize Mac-specific malware, like key loggers
  • Manage hung apps and heavy CPU consumers
  • Update all your software to the latest-supported versions

As you can see, CleanMyMac X does a lot more than just clear out junk files before you backup your Mac. It’s well-worth keeping it on your Mac and using regularly to keep your Mac running smoothly.

2. Save your passwords

When you downgrade mac OS Catalina, you’ll delete everything from your hard drive, including licence keys and settings. So, in addition to making sure you copy all the files that have changed since you last backed up, you should make a note of those. If you use a password manager that syncs with other devices and allows you to store licence codes and encrypted notes, you could use that. If not, any app that allows you to sync encrypted notes will do. Or you can use Apple’s Notes app. It’s also a good idea to take screen grabs of settings to make it easier to restore them later. Remember to copy the grabs to a cloud storage service or an external disk.

3. Create a bootable installer of macOS Mojave

Macos

Note, you can skip this step if your Mac shipped with macOS Mojave or if you made a backup with Time Machine before you upgraded to Catalina.

  1. If you’re reading this before macOS Catalina ships, you can go to the App Store and search for Mojave, then download it. If it tries to install when it’s finished downloading, quite the installer.
  2. If you’re reading this after Catalina ships, you can download Mojave ‎here, but only on a Mac that’s not already running Mojave. When you click that link, Software Update will launch and start to download Mojave. When it’s finished, quit Software Update.
  3. Grab a USB stick with 16GB capacity or an external hard drive or SSD and plug it in to your Mac.
  4. Launch Disk Utilities and Erase the Drive or USB stick, formatting it as Mac OS Extended (Journaled) and selecting GUID partition map if a selection is available.
  5. The easiest way to create a bootable installer is to use DiskMaker X. However, you can also do it in Terminal like this:
  • Launch Terminal from Applications - Utilities
  • Type: sudo /Applications/Install macOS Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled where ‘Untitled’ is the name of your USB stick or external hard drive
  • Press Return and wait for the word Done to appear in Terminal.

Whichever method you used, you should now have a bootable macOS Mojave installer. Keep it safe.

4. Uninstall macOS Catalina

  1. Make sure your Mac is connected to the internet.
  2. Click on the Apple menu and choose Restart.
  3. Hold down Command+R to boot into Recovery mode.
  4. Choose Disk Utility in the macOS Utilities window
  5. Select your startup disk
  6. Choose Erase
  7. Quit Disk Utility

How to downgrade Catalina to Mojave if your Mac shipped with Mojave

  1. Once you’ve erased your startup disk and quit Disk Utility as described above, choose Reinstall macOS from macOS Utilities.
  2. Press Continue.

How to rollback from Catalina using a Time Machine backup

If you backed up your Mac with Time Machine before you installed Catalina, you don’t need to create a bootable installer – you can just reinstall Mojave from your Time Machine backup. Make sure it’s plugged in if it’s an external disk. If it’s a network disk, make sure you’re connected to the network.

  • Once you’ve erased your start up disk as described above, choose Restore from Time Machine backup in the macOS Utilities window.
  • If your backup is on an external disk, select it. If it’s on a network disk, select it and choose Connect to Remote Disk.
  • Type in your username and password for the remote disk if necessary.
  • Select the data and time of the backup you want to restore from.
  • Follow the onscreen instructions.

5. Install Mojave using a bootable installer

If you have a Mac that didn’t ship with Mojave and you don’t use Time Machine to backup, you’ll need to reinstall Mojave from the bootable installer we created earlier.

  1. Plug in the installer disk.
  2. Go to the Apple menu and choose restart, then hold down the Option key.
  3. Mojave will start installing on your Mac.
  4. When it’s finished, your Mac will restart and the Setup Assistant will appear
  5. Follow the steps in the SetUp Assistant to set up Mojave

Restore your settings

If you have reinstalled Mojave from a bootable disk, rather than a Time Machine backup, you will need to reinstall applications and copy documents across from your backup. That’s where those notes and screen shots you made earlier come in handy!

Once you’ve restored your settings and reinstalled all the apps you need, your Mac is ready to use again, running Mojave instead of Catalina.

Tip: If you want to roll back to an earlier version of macOS than Mojave, you can. To reinstall the OS your Mac shipped with, use the method in ‘How to downgrade if your Mac shipped with Mojave’. If you want to roll back to a version of macOS newer than the one your Mac shipped with but older than Mojave, you can download Sierra and earlier versions from the Mac App Store. Then follow from Step 3 in ‘Create a bootable installer of Mojave’.

My Mac is still underperforming, what to do?

You thought that reverting to macOS Mojave would get your Mac back to norm. But if it didn’t and you still experiencing sudden freeze-ups and glitches, full disk cleanup is your answer. Probably there are too many conflicting system junk files on your drive that you need to plow through.

You don’t need a regular disk cleanup app — most of them are scam — but this tool, CleanMyMac X, is notarized by Apple, and can really do helpful optimizations on your Mac.

  • Download the free edition here
  • Go to Maintenance tab


Now you can perform some of the tasks suggested by the app, like running Maintenance Scripts. Also, check the System Junk tab and remove all the useless files it recommends you to delete.

Reinstall

As you can see, it is possible to uninstall Catalina if you decide you don’t want to continue using it. It’s essential, however, that you backup your Mac before you upgrade. And remember, before you backup, clear out the clutter with CleanMyMac X. That way you won’t use precious space on your backup drive copying over junk files.

From Jun 2020 to Aug 2020, Apple has released several beta versions for macOS 11 Big Sur, both developers and testers can install and run it on a supported Mac. You may be one of them, starting to use this new macOS but unfortunately run into some issues and want to revert to previous Catalina or Mojave version.

No worries, here we will list the easy steps to downgrade macOS Big Sur to Catalina without losing data.

Recover Data After Mac Downgrade

  • Recover files lost due to macOS update, downgrade, crash, etc.
  • Recover lost, deleted, formatted data
  • 5 recovery modes: Basic, Advanced, Formatted Drive, Trash, Extenal Devices
  • Recover files from internal and external hard drive (USB, SD Card, Media Player)
  • Support file recovery on 200+ formats: video, audio, photo, docs, etc.
  • Preview files before recovery
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Why We Need to Downgrade Big Sur to Catalina?

MacOS 11 Big Sur is absolutely the biggest update these years since it has moved from 10 to 11, you can find a bunch of update as following in Big Sur:

  • New design
  • Intuitively customized Safari browser
  • Updated Messages app (better control of conversation)
  • Redesigned Maps for better and easier navigation
  • Improved transparency for Mac App Store downloads
  • Expanded photo editing features
  • Faster updates to the latest version

……

All the revealed new updates added to macOS11 Big Sur stimulate mac users to upgrade and take the first bite on this macOS version. But later, there occurs problems and some of them want to revert to the previous Catalina version for one or another reasons:

  • The Beta version is not perfect, you want to download the official version later;
  • It takes longer time to get used to the new version and you don’t want to waste time;
  • MacOS 11 Big Sur keeps causing problems;
  • Your hardware is not highly compatible on this new version (compromised audio, video or image quality);
  • Your favorite app doesn’t work on the new version;

……

No matter what your reason is to revert to an older version, you can refer to following part to downgrade from Big Sur to Catalina without losing data.

How to Downgrade Big Sur to Catalina without Losing Data?

How To Reinstall Mojave From Catalina

To downgrade Big Sur to Catalina without losing data, here are 6 steps to follow. Before the downgrade, your data matters the most, so don’t forget to back them up though it takes time to finish a backup.

Step 1. Prepare your Mac for downgrade

You should quit running programs and leave enough space (15GB to 20GB) to install Catalina after erasing Big Sur from your Mac hard drive. Also, make sure your mac is connected to the internet for later macOS installer download.

Step 2. Backup files (Important and Required)

It is safe to upgrade or downgrade a macOS version, there is no harm done to your files or data, but data loss after mac update or reversion happens sometimes. If you don’t want to render your data under any potential risks, you are highly recommended to back up files.

There are 2 ways to back up file, either back up your files to an external hard drive with Time Machine or upload your data to cloud-based service for storing, like iCloud, DropBox, OneDrive. But here Time Machine backup is recommended.

  1. Connect an external hard drive for backup to your mac;
  2. Run Time Machine and set it up for backup;
  3. Click on the Time Machine icon in menu bar, choose Back up Now;
  4. Wait for the backup to finish.

Step 3. Erase macOS 11 Big Sur from your Mac

  1. Click Apple icon and go to Restart;
  2. Hold down Command+R when rebooting to reboot your mac in Recovery Mode;
  3. In the pop-up interface, choose Disk Utility>Continue;
  4. Then select your Startup Disk, click on Erase tab;
  5. Choose APFS or macOS Extended format and confirm to Erase.

Step 4. Install macOS Catalina or Mojave

There are 3 methods to install older macOS version on your mac.

Method 1. Download from Mac App Store and Install

  1. Launch Mac App Store;
  2. Search macOS Catalina or Mojave, click Download;
  3. When the download finishes, follow the on-screen instructions to install macOS Catalina or Mojave;

Method 2. Reinstall macOS Catalina or Mojave from Internet

  1. Click on Apple logo>Restart;
  2. Hold down Command+R when rebooting your mac;
  3. In the pop-op macOS Utilities interface, choose Reinstall macOS>Continue;
  4. Agree to the terms and follow the instructions to download and install.

Method 3. Reinstall macOS Catalina or Mojave from Bootable Drive

Reinstall macos mojave from catalina download
  1. Create a bootable drive of macOS Catalina or Mojave
  2. Connect the bootable drive to your mac;
  3. Click on Apple logo>Restart;
  4. Hold down Option when rebooting your mac;
  5. Choose the bootable drive with macOS Catalina or Mojave installer;
  6. Click on Continue, agree to the terms and install a previous macOS version onto your mac.

Step 5. Restore Backup with Time Machine

The only change you want for the downgrade is turning back to a previous macOS version, but you want the files and settings the same as before. In this case, you should restore both your files and settings from a Time Machine backup.

  1. Click on Apple Logo>Restart;
  2. Hold down Command+R during mac rebooting;
  3. Choose Restore from Time Machine Backup from the macOS Utilities interface and click on Continue button.
  4. Choose the Time Machine backup disk>Continue;
  5. Select the latest backup, click Restore>Continue.

Step 6. Check if everything is back now!

Now, run your apps on macOS Catalina and check if everything goes well.

If the downgrade still causes problems, restart your mac or reinstall Catalina/Mojave to fix it.

What If Data Lost/Deleted after macOS Big Sur Downgrade?

But what if we still got data lost or deleted after macOS Big Sur downgrade to Catalina or Mojave? You can recover them back with Time Machine backup by following the tutorial in above Step 5. If this still cannot get back your files, you need a professional data recovery program---Cisdem Data Recovery.

Cisdem Data Recovery is a program to recover lost, missing, deleted, formatted files from both internal and external hard drive on mac. It applies to data loss due to system crash, update or downgrade, also supports file systems like APFS, HFS+, FAT16, FAT32, exFAT, NTFS, etc.

Main Features of Cisdem Data Recovery

  • Recover lost, deleted, formatted data;
  • 5 recovery modes enable users to recover files lost under different situation;
  • Recover files from internal and external hard drive (USB, SD Card, Media Player)
  • Support file recovery on 200+ formats: video, audio, photo, docs, etc.;
  • Support various file systems: APFS, NTFS, HFS, FAT, etc.;
  • Preview files before recovery;
  • High recovery rate;

How to Recover Data After macOS Downgrade from Big Sur to Catalina?

Reinstall Macos Mojave From Catalina Os

  1. Download and install Cisdem Data Recovery to your Mac;
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  2. Choose a data recovery mode basing on your need. Basic mode runs a quick scan, while Advanced mode runs a deep scan;
  3. Select the location where you lost the files and click Scan;
  4. Preview the found files; All the founded files will be categorized in different folders, check the file and preview before recovery;
  5. Select the found file and recover them onto your mac. Check the box before found files, stop the scanning process if you want to recover before the end of a scanning process. Click Recover to get all lost files after macOS Big Sur downgrade back to your mac.

Conclusion

No matter you want to downgrade from Big Sur to Catalina or Mojave without losing data, or just want to upgrade from an earlier version to the latest macOS, the backup process is mandatory in case of any data loss. If a data loss happens and you don’t have a backup, you will need a dedicated program like Cisdem Data Recovery to do the job.