How to Reinstall macOS Mojave Without Losing Data?

2018-08-02 22:46:51 / Posted by Connie Wisley to Recover Follow @ Connie

With the release of macOS Mojave, many users are excited to see and experience its impressive and innovative features. For sure, as time goes by, more and more users will join to upgrade to Mojave.

If you have installed Mojave, you may have to reinstall macOS Mojave for some reasons. But how to redownload Mojave? Can I reinstall macOS Mojave without losing data? You will find all the answers and best advices to work efficiently on Mojave.

When to Reinstall macOS Mojave?

1. Reinstall When There is New Mojave Version Available

For each edition of macOS, Apple keeps working constantly to fix bugs, make performance tweaks, add new features or enhance coding. Therefore, doubtless, there will be new versions of Mojave available to upgrade and reinstall. In this case, you are recommended to reinstall and allow Mojave plays at its best.  

2. Your Mac is Running Slow

If you have installed Mojave, but later noticed that your Mac was running extremely slow, let’s say, it takes time to start, to launch programs, to get response from Internet, etc. no matter how many files you have deleted or how many programs you have uninstalled, then a reinstallation of Mojave is needed. As we all know, for no specific reason, system reinstallation can magically solve a slow Mac in most cases.

3. Your System Keeps Crashing or Works Improperly

When you continuously see error messages appear on your mac, or your programs randomly crash/freeze for no reason, even you notice that your FaceTime won't work, the information saved in your Contacts or Calendar shows a delay or mess, your keyboard behaves erratically, your blue teeth or WiFi won't connect like before…Then, you have a good reason to reinstall Mojave on your mac to shoot all these troubles.

4. You are Going to Sell the Mac 

In the case that you want to sell your mac, besides erasing all your personal data and traces on the mac, you will need to reinstall Mojave as well. A reinstallation will create a new copy of Mojave for your mac, which in one hand helps to optimize the performance of your Mac, and prepare your mac as new as possible for its new owner in the other hand.

How to Reinstall macOS Mojave without Losing Data?

We all save tons of data on our Mac, so when we decide to reinstall macOS Mojave, the top concern always goes to “will I lost everything if I reinstall macOS”. Consequently, here we are going to talk about how to reinstall macOS Mojave without losing data.

In fact, reinstallation of macOS Mojave doesn’t necessarily cause lost data, it just create a new copy of Mojave, your existing files and data saved in programs won't be altered or deleted. But just in case of bad luck, we need to do some work on BACKUP, this is crucial for Mojave reinstallation without losing data.

Step 1. Prepare Your Mac for Reinstallation.

Make enough room for Mojave reinstallation, so the reinstallation process won't pause or stopped for insufficient space. Also, quit all apps or programs under work, so your Mac is fully geared to reinstall.

Step 2. Backup All Your Files (Crucial)

Backup is an indispensable step involved in the Mojave reinstallation, here are several options to backup your data.

Option One: Using Time Machine

  1. Go to Finder>Application, launch Time Machine and choose “Set Up Time Machine”.setup time machine
  2. Click “Select Backup Disk” to choose an external hard drive to back up the files.back up with time machine
  3. Then Check the box before “Back Up Automatically”. Also, you can adjust the backup setting in menu “Options”.

If this is the first time you use Time Machine to backup, wait patiently for Time Machine to complete the backup, it will prompt the notification once finishes.

backup complete


Option Two: Using Hard Drive 

  1. Connect your hard drive to Mac.
  2. Open Finder to check if your hard drive is present under “Devices”.
  3. Create a new folder, copy and paste or directly move the items you want to save from Mac to this folder.
  4. Finally, eject your hard drive.


Option Three: Using iCloud Service (Backup Desk and Documents Folders)

  1. Go to Finder>System Preference, click on “iCloud” to bring up its main interface.back up with icloud
  2. Click the “Options” button for “iCloud”, and check the box before “Desktop and Documents Folders”, then click on “Done”.back up with icloud 02

Most of our mac users prefer to backup all files but apps. So, to save you from troubles of lost data due to Mojave reinstallation, you are recommended to keep records of what apps you have installed, the account and password, also, you can take screenshots of the settings.


Step 3. Reinstall  macOS Mojave without Losing Data.

  1. Click the Apple icon>Restart.restart to reinstall
  2. Hold down the key combination: Command+R, you will see the Apple logo.
  3. Then choose “Reinstall macOS” and click “Continue”.reinstall Mojave without losing data
  4. Select your hard drive, click “Install” and wait for end of reinstallation.

What if You Lost Data After Reinstallation?

However, losing data after reinstallation still happens. It may result from a interrupted installation (power-off/poor internet connection), corrupt setup, insufficient space or improper actions. Then, what to do if you lost data after reinstallation? Here are 2 methods.

Method 1: Use Time Machine to Recover Data

If you have backed up your files on mac, you can use Time Machine to restore the lost data.

  • Step1. Go to Finder>Applications>Time Machine, launch it and choose “Enter Time Machine”. 
  • Step2. In the popped-up window, use the arrows and timeline to browse the local snapshots and backups.recover with time machine
  • Step3. Find the deleted files, then click “Restore” to recover the lost data caused by reinstallation.

Method 2: Use Cisdem Data Recovery to Recover Data

While, in the case Time Machine fail to recover the lost data, or you didn’t do backup before reinstallation, you will need a dedication data recovery program to find the lost data for you.

Here we recommend Cisdem Data Recovery, a powerful mac program allowing users to recover lost/deleted/corrupted/formatted files from a wide range of external or internal storage devices, no matter the file is lost due to human errors, power-off, reinstallation, upgrade, virus attack or disk crash.

Steps to Recover Lost Data after MacOS Mojave Reinstallation

  1. Download and install Cisdem Data Recovery on Mac.
    Free Download
  2. Choose a Recovery Mode according to your need.
    If you want an efficient recovery, choose “Basic Data Recovery”, if you want to recover files with a higher success rate, try “Advanced Data Recovery”.choose a mode
  3. Select the hard drive where you originally stored the files on mac. Then click “Scan”.choose a disk
  4. Check and preview files found by Cisdem Data Recovery.found files
  5. Select files to recover.
    Check the box before files that you want to recover, then click “Recover” to find back the lost data caused by reinstallation.recover files by cisdem


The key to reinstall mac OS Mojave without losing data is the backup, since no one can guarantee all data will be perfectly maintained after mac OS Mojave reinstallation. However, if we unfortunately lost files after Mojave reinstallation, Time Machine or Cisdem Data Recovery is helpful to recover them back.

So, do you have any other tips to reinstall mac OS Mojave without losing data? Please share with more of our mac users.

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