First of all, coming on to the process to Reinstall macOS.
The procedure is as follows:
- The first step is to turn your Mac on while holding the Command + R keys down.
- Now, select “Disk Utility” and click on Continue.
- Select >> start-up disk and go to the Erase Tab.
- Select >> Mac OS Extended. And give a name to your disk and click on Erase.
- Disk Utility >> Quit Disk Utility.
- Re-installation of MAC OSX: click >> “Reinstall Mac OS X” >> “Continue“.
- And follow the on-screen instructions.
1: Backup Files on Mac
You should take a backup of your data beforehand if you don’t want to suffer from an unexpected loss of your important files during the reinstallation. There are different ways to backup data on Mac:
Backup files Using Time Machine
If you do not want to let go of your important files during the reinstall macOS process, then consider taking their backup beforehand. Mostly, Time Machine will detect a connected unit and would ask you to take its backup automatically otherwise follow these steps to back up your Mac data using Time Machine.

- Simply connect a secure data storage to your Mac and launch Time Machine by visiting Menu >>> System Preferences >>> Time Machine.
- Now, click on the “Select Backup Disk” to manually choose a location to save the backup content.
- As a pop-up screen would appear, just select the available drive and confirm your choice. If you want, you can choose to encrypt your data as well.
- For further customization, you can visit its “Options”.
- As a pop-up screen would appear, just select the available drive and confirm your choice. If you want, you can choose to encrypt your data as well.
Backup files Using Cloud Storage
If you want to save your data on the cloud, then take the assistance of iCloud, Google Drive, Dropbox, OneDrive, or any other cloud-based service. Since iCloud is the native cloud storage solution from Apple and an inbuilt Mac app. You can easily backup files to iCloud from Mac by following these steps.
- Go to system preferences and launch the iCloud app and then log in.
- The iCloud app has options to sync various data types. Simply enable the features and turn on the backup feature.
- You can go to the “Manage” section to view how much space is left on iCloud.
Backup files Using External Hard Drive
You can also take a manual backup using an external hard disk. Just connect the hard disk to your Mac and make sure that you are using a compatible hard drive with your macOS. Now, simply copy the content from your Mac’s storage that you wish to save and paste it to the external hard disk. In this way, you would be able to maintain a second copy of all the important data.
The process to Reinstall macOS has become easy by MAC OS Recovery. All you need is a connection to the Internet. If a wireless network is available, you can choose it from the Wi-Fi menu in the menu bar. Steps are clearly mentioned below:
The very first steps are starting with MAC OS recovery:
- Turn on your Mac and immediately press and hold one of the following combinations on your keyboard. Generally, “Command+ R” is recommended, especially if your Mac was never been upgraded.
- “Command + R”- Reinstalling the latest MAC OS that was installed on your MAC (recommended).
- “Option+ R”- for Upgradation to the latest MAC OS that is compatible with your MAC.
- “Shift + R”- this is to reinstall macOS that came with your MAC, or the closest version still available.
- when you see an Apple logo, spinning globe, or another start-up screen then, release the keys.
Decide whether to format your disk
Select Disk Utility from the utility window if you need to erase your disk before installing MAC OS and then click Continue.
Installation of macOS
Choose Reinstall macOS (or Reinstall OS X) from the utility window after starting up from MAC OS recovery. Then click Continue and then follow the onscreen instructions to choose your disk and start the installation procedure.
Enter the password you use to log in to your Mac if the installer asks to unlock your disk. The installer doesn’t see your disk, or it says that it can’t install on your computer or volume, you might need to erase your disk. Allow the installation to complete without putting your Mac to sleep.
- Now, coming on to the installation of MAC OS high sierra. Here are the steps to reinstall macOS Sierra or MAC OS High Sierra by doing the following:
- Backing up the MAC.
- Rebooting the MAC and holding it down COMMAND + R keys concurrently right after you hear the boot sound, this will boot the Mac into Recovery Mode.
- choose “Reinstall macOS” at MAC utilities.
- Click “Continue” and carry on to the setup screen.
At the drive selection screen and choose whatever the name of your hard drive is. This is the drive where macOS Sierra will be reinstalled. And then click on “Continue” or “Unlock” if you use file vault.
The screen will turn black and an Apple logo once the reinstallation process begins, a progress bar will appear.
After reinstallation has completed, macOS Sierra / High Sierra will automatically boot up as usual.
- Almost it takes 30 minutes to 3 hours to reinstall macOS.
- During the reinstallation process, your Mac might be overheated or restart multiple times.
- There are chances are that your existing data on Mac might be deleted after the reinstallation. Thus, you can consider taking its backup if you don’t want to lose it.
- Disconnect all the attached units like USB drive, SD card, etc. from your Mac beforehand.
- Keep your Mac connected to a stable internet connection for a seamless updating.