This page covers the full process of how to update and install the latest macOS Big Sur, Catalina, Mojave, etc. on Mac without losing any data. If you need a detailed guide, follow through this page to get the desired macOS installed on your computer now:
Installing iShowU Audio Capture on Mojave/Catalina. Download the iShowU Audio Capture installer. Once the download has finished, find the installer - it should be in your Downloads folder. Double click to open the package, and run the installer. Press the Continue button. Note that reinstalling macOS Mojave with this approach is not the same thing as performing a clean install. A clean install of Mojave erases literally everything on the computer, including personal data, by using a bootable Mojave installer drive, while reinstalling aims to simply reinstall only the macOS operating system itself. After that, quit Terminal and click Reinstall macOS to run the Catalina/Mojave installer again. Solution 3: Install the Full Version of Mojave/Catalina Installer. I upgraded or rather installed Catalina but I installed it on another partition on my HD. I install or transfer apps, from my Mojave drive onto my Catalina drive. I can now test any app, for functionality and compatibility. If there are issues they can be sorted but I can still rely on Mojave to get on with what I need to do. After installing Mojave I figured I could run the migration assistant to pull all of the data from my Time Machine backup into the latest copy of Mojave. This approach mostly worked until I started browsing the web. The migration assistant pulled over the Catalina version of Safari which would not run on Mojave.
| Workable Solutions | Step-by-step Troubleshooting |
|---|---|
| Phrase 1. Preparations | 2GB+ memory and 9GB+ storage space left on Mac > 45% + battery > Connect to internet...Full steps |
| Phrase 2. Change a USB port | Start Mac from macOS Recovery > Select 'Reinstall macOS' > 'Continue'...Full steps |
| Phrase 3. Recover Lost Data | After macOS installation, run EaseUS Mac data recovery software > Scan and recover lost data...Full steps |
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 on their computer.
The good news is that, if you follow the instructions strictly to update your Mac Operating System, the chance to lose data on your Mac is quite slim, since a reinstallation just needs to create a new copy of the OS, your existing files stored on your Mac won't be lost. Thus, as long as you don't choose to erase your startup disk during the reinstallation, you won't lose files. However, you know what 'Slim' means - it's not 100% safe and is still at the risk of losing some data.
Then how to reinstall macOS without any data loss? To provide a double guarantee to the precious data on your Mac, you can make a copy of the files on your Mac before you perform the reinstallation, or equip your Mac with a data recovery tool that can rescue your data after the reinstallation.
Preparations you Need to Make Before You Reinstall macOS
To reinstall macOS on your computer smoothly. Follow the tips below to prepare your Mac ready for the new macOS update now:
- Leave at least 2GB memory and 8.8 GB storage space on your Mac
- Leave at least 45% battery on your Mac
- Connect Mac to the internet or WiFi
- Update your Mac Apps to the latest versions
- Backup all your personal data and even create backups for your present Mac data through Time Machine
How To Reinstall Mojave From Catalina
Remember to back up your Mac to an external hard drive for preventing system update failure or unexpected troubles from happening. Then follow the detailed guide below to reinstall Mac OS via macOS Recovery mode, which enables you to reinstall macOS, restore your files from Time Machine, repair or erase a disk, and more.
How to Update & Reinstall macOS Without Losing Data
*Print this page or open this page on another device so you can refer to it later.
Step 1. Start up your Mac from macOS Recovery
- Turn on your Mac and immediately press and hold 'Command + R', 'Option + Command + R', or 'Shift + Option + Command + R'.
- Release the keys when the Apple logo, a spinning globe, or a pop-up for a firmware password appears.
Step 2. Select 'Reinstall macOS' from the Utilities Window and click 'Continue'.
Step 3. Follow the onscreen instructions to select the hard drive you want to install the OS on and start the installation.
Step 4. Don't put your Mac to sleep mode or close its lid during the installation. It's normal to see your Mac restart several times or the screen is white while you reinstall the Mac OS. Just wait patiently for the process to finish.
If data loss occurred after you reinstalled macOS, you can follow the next part to recover your missing files.
Recover Lost Data After macOS Reinstallation
If you have backed up your Mac before the reinstallation, you can retrieve your data from Time Machine, an external hard drive, or somewhere else, depending on the way you used to make the backup. If you haven't created any backups for your Mac, then you'll need the professional Mac data recovery software tool - EaseUS Data Recovery Wizard, to perform data recovery. With the help of this tool, you can easily recover the data lost due to macOS reinstallation:
Step 1. Select a location and start scanning
Launch EaseUS Data Recovery Wizard, hover on the location where you lost data, then click 'Scan'.
Step 2. Preview and select the files
Wait until the scanning completes. You can use Filter or search bar to find lost files.
Step 3. Recover lost data
Then choose a location to save the recovered data, and click 'OK'. You should store the data in another place instead of the original one.
Can I Reinstall Mojave From Catalina
There are lots of data recovery tools available. But EaseUS Data Recovery Wizard, one of the best Mac data recovery tools, is our pick. It fully supports all macOS systems including the newest Big Sur, Catalina, Mojave, High Sierra, Sierra, EI Capitan, Yosemite etc. It allows you to restore all lost data with simple clicks. Office files, music, videos, emails or other archives can all be restored on your own.