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Recovering Data after Mac OS Update, Reinstall or Disk Format

The majority of Mac users claim that the most widespread case of data loss is when the operating system is updated or reinstalled, or when the hard disk is formatted.

Recovering Data after Mac OS Update, Reinstall or Disk Format


The need to reinstall the operating system may arise after a system error, when the computer works too slowly, or when you need to erase all personal data.

From this article, you will learn how to recover data after reinstalling macOS or formatting the hard disk. Below, you will also find a complete guide to help you reinstall MacOS safely without losing any data at all.


If you decided to reinstall the operating system and format the hard disk in the process, you should backup important data in advance to save yourself the trouble of trying to recover it somehow. This would be the best way to secure your data against possible loss.

However, sometimes having a backup copy is not enough to recover lost or removed files, as there could always be some unpredictable things.

During the reinstall, the operating system performs a quick erase operation on the corresponding volume. As a result, it removes the file catalog but doesn’t write anything to the hard disk, so that the original data doesn’t get overwritten.

This peculiarity lets you recover files after reinstalling the Mac operating system – if you start recovery operations immediately.

Remember to stop using the hard disk where the important information used to be stored, otherwise it will be lost after overwriting.

How to recover files after reinstalling macOS

Without using additional software tools data recovery after reinstalling the operating system is only possible if you have created a backup in advance.

There are several ways to recover lost data. Choose one depending on your circumstances.

Recovery from a Time Machine backup stored on an external drive

The first method to bring back the lost files after reinstalling the operating system is to restore a backup from Time Machine. If you have already created a backup on an external hard disk, you can handle the lost data issue easily.

This way, you have almost 100% guaranteed chance for recovery.

Here is what you should do:

Step 1. Make sure that the external hard disk with a Time Machine backup is connected to your Mac device.


Step 2. Open Launchpad, click Other. Find the Time Machine icon and click on it.


Step 3. Use up and down arrow keys to move the timeline and view backups containing the lost files.


Step 4. Find the lost data that you need to bring back and click Restore.


It starts the recovery process.

After that, you may have to restart the computer, and then the files should appear on the disk and become available for viewing.

Recovering files from an iCloud backup after OS reinstallation or after disk formatting

Another method of data recovery after reinstalling the operating system is by using an iCloud backup.

This method is applicable if you uploaded a copy of important data to iCloud before reinstalling the operating system.

If that’s the case, restoring the information is very easy.

Do the following to recover data from an iCloud backup:

Step 1. Open the browser and go to, use your Apple ID to sign in.

Step 2. Open the settings and go to Advanced and click Restore files.

To restore contacts, bookmarks and reminders from the calendar, click on the corresponding settings in Advanced.

Step 3. Select the necessary backup or click to Select All, if you need to have all the files back. After that, click Restore.

When the process is over, all the files you have uploaded to iCloud before they were lost while reinstalling macOS will appear on your computer again.

File recovery with third-party tools after reinstalling MacOS or disk formatting

This method requires using a computer with Windows operating system. If you haven’t created a backup in Time Machine before reinstalling macOS, you will need to download a special utility to help you recover your data.

With virtually tons of data recovery tools offered on the Internet, we recommend using our product, Hetman Partition Recovery. When it comes to recovering files after reinstalling an operating system, you can rest assured that Hetman Partition Recovery will do the job perfectly.

It will scan the hard disk or external storage device, find the lost data and help you recover it in a simple and efficient way.

Here is what you do to get your data back:

Step 1. Connect your disk to another computer with a Windows operating system, download and install Hetman Partition Recovery.

Hetman Partition Recovery

As I said before, during the reinstalling process, the operating system performs a quick wiping operation on the corresponding volume. As a result, it removes the file catalog but doesn’t write anything to the hard disk, so that the original data doesn’t get overwritten. However, remember to stop using the hard disk where the important information used to be stored, otherwise it will be lost after overwriting.

Step 2. In the Drive Manager, select the storage device, right-click on it and choose Open. Try a fast scan first – it will take less time. If the fast scan doesn’t help to find the deleted data, then go for Full analysis.

Hetman Partition Recovery

Step 3. The file recovery wizard will scan the selected volume immediately and display the scan results in the right side of the program’s window.

Hetman Partition RecoveryHetman Partition Recovery

Step 4. When the scan is over, all you need to do is to select the deleted files you want to restore and then click Recovery. Specify where to save the data and click the same button again to start recovering.

Hetman Partition RecoveryHetman Partition Recovery

Also, this program can create a disk image and the conduct all recovery operations with this image which increases your chances to restore the deleted information successfully, because multiple rounds of scanning may result in data overwriting.

Hetman Partition Recovery is a powerful, safe and easy-to-use data recovery tool, and that’s why we recommend using this specific product. Before trying it, you are welcome to watch a video where we compare various tools of the kind and our product shows one of the best results.

Video: Testing top recovery tools.

You can use this program for data recovery in any of the following cases:

  • To recover files lost after removing or formatting partitions, system errors, virus attacks and other scenarios that involve loss of data.
  • To recover data from internal and external hard disks, USB storage devices, SD memory cards, cameras and other devices used to store information.
  • To recover lost photos, videos, music, documents and other file types.

Backing up and reinstalling the operating system without losing data

All in all, it’s always a good idea to back up the valuable information you store on the hard disk before reinstalling the operating system. In the end, it helps to never lose important data and avoid unnecessary trouble. Even though it may seem a bit difficult and is sure to take some time, you won’t have to spend lots of time and effort later when you realize the data has to be recovered somehow.

For example, copy your important files to a removable drive.

To save your time, use the built-in Time Machine feature, or upload the information to iCloud.

When it’s done, you can start the reinstallation process without worries.

To reinstall the operating system:

Step 1. Restart the computer into the recovery mode.


Step 2. Clean the hard disk

To do it, open Disk Utility and click Continue


Select the boot drive and click Erase> Select Mac OS Extended or APFS and click Erase.


Step 3. Repeat Step 1 to open macOS utilities. Click Reinstall macOS, then Continue to start the process. Follow wizard directions to complete it.


In the end, your computer gets a clean installation of the operating system.

Step 4. To recover data, open Time Machine and restore the information from the backup file.



Now you know how to recover lost data after you reinstalled your MacOS or formatted the hard disk. If you don’t have a system backup, use a third-party data recovery tool – Hetman Partition Recovery, and the program will scan the disk, find and display the deleted data, so you will only have to decide where to save it.

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