Can I reinstall MacOS without losing my data?

Yes, it's possible to reinstall MacOS without losing your data, but it requires performing what's known as a 'non-destructive' or 'in-place' reinstallation. This method reinstalls the MacOS system files while leaving your user data, applications, and settings intact. Here's how you can do it: Backup Your Data: Before proceeding with any reinstall, it's always recommended to back up your important data. While the risk of data loss during a non-destructive reinstall is low, it's better to be safe than sorry. You can use Time Machine or manually copy your files to an external drive. Boot into Recovery Mode: Restart your Mac and hold down Command (⌘) + R keys simultaneously until you see the Apple logo or a spinning globe. This will boot your Mac into Recovery Mode. Access Disk Utility: Once in Recovery Mode, select 'Disk Utility' from the Utilities menu and click 'Continue'. Select Your Startup Disk: In Disk Utility, select your Mac's startup disk (usually named 'Macintosh HD') from the list of drives on the left-hand side. Choose Reinstall MacOS: Close Disk Utility and choose 'Reinstall MacOS' from the macOS Utilities window. Follow the on-screen instructions to proceed with the reinstallation. Follow the Prompts: The MacOS installer will guide you through the reinstallation process. Make sure to select your startup disk as the destination and follow any prompts related to installation settings. Complete the Installation: Once the installation is complete, your Mac will restart into the newly installed MacOS. Your user data, applications, and settings should remain intact. Restore Data (If Necessary): After reinstalling MacOS, you can restore your data from your backup using Time Machine or by manually copying files back to your Mac. By following these steps, you can reinstall MacOS without losing your data. However, it's essential to ensure that you have a recent backup of your data before proceeding with any system changes.

How do I create a bootable MacOS installer USB drive for a clean installation?

Creating a bootable MacOS installer USB drive is a straightforward process and requires a few simple steps. Here's how you can do it: Download MacOS Installer: First, you'll need to download the MacOS installer from the Mac App Store. Go to the App Store on your Mac and search for the version of MacOS you want to install (e.g., macOS Catalina, macOS Mojave). Once downloaded, the installer will automatically launch, but you can quit it for now. Format USB Drive: Insert a USB drive with at least 12 GB of free space into your Mac. Open Disk Utility (Applications > Utilities > Disk Utility). Select USB Drive: In Disk Utility, select your USB drive from the list of drives on the left-hand side. Erase USB Drive: Click on the 'Erase' button in the toolbar. Choose a name for your USB drive, select 'Mac OS Extended (Journaled)' as the format, and 'GUID Partition Map' as the scheme. Then, click 'Erase' to format the USB drive. Open Terminal: Once the USB drive is formatted, open Terminal (Applications > Utilities > Terminal). Create Bootable USB Drive: In Terminal, type the following command to create the bootable MacOS installer USB drive: sudo /Applications/Install macOS [Your macOS Version].app/Contents/Resources/createinstallmedia --volume /Volumes/[Your USB Drive Name] --nointeraction Replace '[Your macOS Version]' with the name of the MacOS installer app you downloaded (e.g., 'Install macOS Catalina.app') and '[Your USB Drive Name]' with the name of your formatted USB drive. Authenticate: Press Enter and then enter your administrator password when prompted. Terminal will begin creating the bootable MacOS installer on the USB drive. This process may take some time, so be patient. Completion: Once Terminal displays 'Done,' the bootable MacOS installer USB drive is ready for use. You can now use the bootable USB drive to perform a clean installation of MacOS on your Mac by restarting your Mac while holding down the Option (⌥) key and selecting the USB drive from the boot menu. Follow the on-screen instructions to complete the installation.

What steps should I take to back up my data before performing a clean MacOS installation?

Before performing a clean MacOS installation, it's crucial to back up your data to ensure you don't lose any important files. Here are the steps you should take to back up your data: Identify Important Data: Take some time to identify the files, folders, and applications that contain important data you want to back up. This may include documents, photos, videos, music, emails, bookmarks, and any other personal files. Use Time Machine: Time Machine is a built-in backup feature in MacOS that makes it easy to back up your entire system. Connect an external hard drive to your Mac and set up Time Machine to create a full backup of your data. You can configure Time Machine in System Preferences > Time Machine. Manually Back Up Files: In addition to using Time Machine, consider manually backing up specific files and folders to another external hard drive, cloud storage service, or network-attached storage (NAS) device. Simply copy and paste the files you want to back up to the external drive or cloud storage. Verify Backup Completeness: Once the backup process is complete, take some time to verify that all your important files have been successfully backed up. Double-check that your Time Machine backup includes all the necessary data and that your manual backups are complete. Create a Backup of Application Data: Some applications store data in specific locations on your Mac. If you have important application data (e.g., email archives, browser bookmarks, preferences) that you want to preserve, make sure to back up these files as well. You can usually find application data in the 'Library' folder in your user directory. Check Backup Integrity: After backing up your data, it's a good idea to check the integrity of your backups to ensure they're reliable. Test restoring a few files from your Time Machine backup or manually copying files from your external drive to verify that everything works as expected. Store Backup Safely: Store your backup drives or cloud storage credentials in a safe and secure location, away from potential hazards like water, fire, and theft. Consider keeping one backup offsite for added protection. By following these steps, you can ensure that your data is safely backed up before performing a clean MacOS installation, giving you peace of mind during the process.

Will reinstalling MacOS erase all the applications installed on my Mac?

Reinstalling MacOS can be done in different ways, and whether or not it erases your applications depends on the method you choose: Reinstalling MacOS from Recovery Mode: When you reinstall MacOS from Recovery Mode, it typically reinstalls the operating system files while leaving your user data, applications, and settings intact. In this case, your applications should remain installed after the reinstallation is complete. Performing a Clean Installation: If you opt for a clean installation of MacOS, where you erase the entire startup disk before reinstalling MacOS, then yes, it will erase all applications installed on your Mac. A clean installation wipes the disk completely, removing all data and applications, so you'll need to reinstall your applications afterward. It's essential to understand the distinction between reinstalling MacOS from Recovery Mode and performing a clean installation. If your goal is to retain your applications and user data, you should choose the reinstall MacOS option from Recovery Mode. However, if you want to start fresh with a clean slate, you'll need to perform a clean installation, which will require reinstalling your applications afterward.

How long does it take to reinstall MacOS with a clean installation?

The time it takes to reinstall MacOS with a clean installation can vary depending on several factors, including the speed of your Mac's hardware, the version of MacOS you're installing, and your internet connection speed (if downloading MacOS from the internet). However, on average, the process typically takes between 30 minutes to an hour or more. Here's a rough breakdown of the time involved in each step of the process: Downloading MacOS Installer: If you're downloading the MacOS installer from the internet, the download time will depend on the speed of your internet connection and the size of the installer. This step can take anywhere from a few minutes to several hours, depending on these factors. Creating a Bootable Installer (Optional): If you're creating a bootable installer USB drive, the time it takes to complete this step can vary but usually takes around 15-30 minutes. Erasing and Formatting the Disk: Erasing and formatting the disk as part of the clean installation process typically takes a few minutes. Installing MacOS: The actual installation of MacOS can take anywhere from 20 minutes to an hour or more, depending on the speed of your Mac's hardware and the version of MacOS you're installing. During this time, your Mac may restart multiple times as it installs the operating system files. Setting Up MacOS: After MacOS is installed, you'll need to go through the initial setup process, which includes configuring your language, region, keyboard preferences, Wi-Fi network, and Apple ID. This setup process can take another 10-20 minutes. Overall, while the exact time can vary, you can typically expect the entire process of reinstalling MacOS with a clean installation to take anywhere from 30 minutes to a few hours, depending on the factors mentioned above.

Do I need an internet connection to reinstall MacOS from scratch?

Yes, you will need an internet connection to reinstall macOS from scratch. The installation process requires downloading the necessary files from Apple's servers to create a bootable installation drive. Additionally, an internet connection may be needed to activate macOS and download any updates during the installation process.

How to Reinstall MacOS: A Step-by-Step Guide

Author: Vladimir Artiukh
Editor: Oleg Afonin
Updated: 10.09.2024 10:55

Learn how to reinstall MacOS for a clean operating system installation. Whether you’re experiencing issues with your current MacOS setup or simply want to start fresh, this step-by-step guide will walk you through the entire process. From preparing your Mac for reinstalling MacOS to performing the clean installation, we’ve got you covered.

How to Reinstall MacOS: A Step-by-Step Guide

Contents

There are a few reasons why you might need a clean installation.

You may wish to reinstall the operating system to fix certain problems with your Mac, since clean installation can be helpful if your computer doesn’t work properly.
The clean installation allows you to delete old files that have been accumulating for years.
Also, you should perform a clean installation before selling your Mac or giving it to a new owner. This way, you can remove all your personal data and factory reset the computer.

Whatever your reason, reinstalling MacOS can help to solve a number of issues.

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How to find out if you need a clean installation

Until recently, reinstalling the operating system was useful if you wanted to fix certain issues pestering your Mac, but now this method makes little sense. If you feel your computer is experiencing certain issues, just reset it without reinstalling the system.

MacOS can’t be modified by any user-installed software. That is why system reinstallation is only required when macOS refuses to boot.

There are several ways to run a clean installation for macOS. A typical method involved creating a bootable copy of the macOS installer on a USB drive and then formatting the hard disk before installing the operating system. Another method is even simpler – using macOS Recovery to reinstall the operating system. It will help you restore operability of your computer even without using a bootable pen drive with macOS.

MACOS Recovery™ 2.6

Recover data from pen drives, memory cards, HDDs and SSDs in macOS.

Download

Besides, if you use macOS Monterey or a later version on M1, M2 or Intel processor with T2 security chip, there is an option in System Settings to reset the system without reinstalling. This method will help you get a clean operating system – it’s a kind of a factory reset option.

How to reinstall MacOS with a bootable USB drive

For starters, let’s find out how to reinstall MacOS with a bootable USB drive.

Step	Action	Description
1	Create a data backup	Use Time Machine or another backup tool to save all important files.
2	Sign out of accounts	Sign out of iCloud, iTunes, and other services to avoid potential authorization issues after reinstallation.
3	Check Internet connection	Ensure that the MAC has a stable Internet connection for downloading the operating system.
4	Create a bootable disk	Download the official macOS image and create a bootable USB drive using Terminal or other tools.
5	Check disk status	Use Disk Utility to check and repair the disk to ensure it is ready for reinstallation.
6	Reset PRAM and SMC	Perform PRAM and SMC reset to avoid potential hardware issues during reinstallation.
7	Start reinstallation	Restart the MAC and begin the system installation from the bootable disk, following the on-screen instructions.

Before you proceed, make sure you have backed up all important data. This can be done with the Time Machine or in some other way. Also, make sure that you have Internet access to download a required macOS image. You will also need a flash drive with the capacity of at least 16 GB.

Download the macOS image from App Store. In the search filed, type the version of the operating system and click Get, then Download. Wait for the download to finish.

After that, create a bootable USB drive with the help of Terminal. Open: Launchpad – Apps – Other – Terminal.

Type the following command in Terminal:

sudo /Applications/Install\ macOS\ Ventura.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

You need to specify the version of the operating system and the name of the drive where the system image should be written, that is, your USB drive. Press Enter to continue.

When you see the message that this volume will be erased, type yes to confirm this action.

When this step is complete, connect the bootable USB drive to the Mac where you need to reinstall the operating system, and start the computer.

Connect the bootable USB drive to the Mac, and start the computer

To boot from the USB drive, press and hold the Option key and choose to boot from USB.

If you see the following message when booting from the USB drive:

Security settings do not allow this Mac to use an external startup disk. You can change this by restarting and holding down Command-R to open macOS Recovery, and then choosing Startup Security Utility.

It means that security settings need to be modified.

To modify them, restart the computer while you press and hold the key shortcut Comand + R. In the Recovery window, open Utilities – Startup Security Utility.

Check the box next to Medium Security and below – Allow booting from external or removable media.

Medium Security, Allow booting from external or removable media

Then click on the Apple icon and boot your Mac while holding down the Option key. When the security settings are modified, you will be able to boot from removable media.

After that, click on Install macOS, in my case, it’s Ventura, and then click Continue.

Now agree to the license agreement and choose the disk where to install the operating system. Click Continue.

In the course of installation, your Mac will restart several times. As a result, you will get a computer with a clean operating system. Now you have to configure it, choose your region, language, keyboard layout and so on.

This method will also help you if you need to install a macOS version which is earlier than the one you are using at the moment. Just download the corresponding bootloader from AppStore.

How to reinstall the operating system with the help of macOS Recovery

One more effective way to reinstall macOS is to use the integrated recovery mode.

macOS Recovery is a specially designed feature that lets you recover the operating system even if your computer can’t boot automatically. This mode can be used to reinstall the operating system, clean your MacBook, reset system settings, recover data from a Time Machine backup and so on.

For starters, shut down your computer. Hold down the keys Command + R (for Intel Mac) or the power button (for Apple Silicon), and start it again. Hold down the key or buttons until you see the Apple logo on the screen.

As the computer boots, the macOS Utilities screen will appear where you can choose the necessary option:

Restore from Time Machine: it lets you recover the operating system and data from a previously created backup file.
Reinstall macOS: it lets you reinstall the operating system without removing your files.
Disk Utility: it lets you check, restore or erase disks and partitions on your computer.
Safari: if you have an active Internet connection, it will help you find additional information on the Apple Support website. In the recovery mode, Safari plugins and extensions will be disabled.

To connect to the Internet, click on the Wi-Fi icon in the upper right corner of the screen, choose a network and enter your password.

Now the recovery mode is connected to the Internet, so if necessary, you can use the browser or the operating system will be able to download additional software installers.

If you want to erase all data from this Mac before installation, open Disk Utility.

To erase all data, you should delete the volume Macintosh HD; depending on the version of your operating system, there may be several volumes. The most important thing is to never delete the boot partition - but usually, it’s relatively small and has an appropriate name.

After formatting the hard disk, press Command + Q, to go back to macOS Utilities, and then click Reinstall macOS.

If you don’t want to erase the disk, you can click on Reinstall macOS to start this process immediately. At this stage, you may be prompted to type your Apple ID or Mac password. Click Continue, and agree to the terms of the software license agreement.

Click Continue, and agree to the terms of the software license agreement

Now choose the disk where to install the operating system, and click Continue. The reinstallation process may take some time.

When it’s complete, you will see the sign-in screen. Now you have a fresh and clean macOS.

This method will also help you to restore the system’s operability if there is anything that prevents it from booting.

Erase All Content & Settings

Another method to get a clean operating system is to use the option Erase All Content & Settings in the System Settings of your Mac. This option is available in macOS Monterey or Ventura and later versions based on Mac M1, M2 or Intel Mac with the T2 security chip. For any Mac without the T2 chip, use the previously described method.

Before you reset the system, it is strongly recommended to create a backup in case anything goes wrong.

To clean the operating system, with the example of MacOS Ventura, open System Settings. Go to General tab and click on Transfer or Reset.

System Settings – General - Transfer or Reset

Then click on - Erase All Content and Settings.

The system will ask for your account password. Type your password, then click Unlock, and Continue to proceed.

Type the password, then click Unlock and Continue

After that, you will see a warning window saying that all your data will be erased. Click Erase all content & settings to confirm it.

As a result, the computer will restart several times, and you will finally see the Activate Mac window. When the activation is successful, click on the Restart button.

When the computer boots again, you will see the welcome screen.

At this stage, you will be able to set up your operating system as you would do for a new device, or just shut down and leave it as it is, so that another user can complete the configuration process, if you have reset the computer for a new owner.

Pros and Cons of Clean Install and Factory Reset on macOS

Clean Install

Pros:

Ensures a fresh start for your Mac.
Eliminates any potential software conflicts or corrupted files.
May improve overall system performance.
Provides an opportunity to declutter your system.
Ideal for upgrading to a new version of macOS.

Cons:

Requires reinstalling all applications and restoring data.
Time-consuming process.
Risk of losing data if not backed up properly.
Can be daunting for less experienced users.

Factory Reset using macOS Recovery

Pros:

Restores your Mac to its original state.
Retains essential system files and configurations.
Simplifies the process compared to a clean install.
Useful for troubleshooting persistent issues.
May resolve software-related problems effectively.

Cons:

May not completely resolve deep-seated issues.
Retains any accumulated clutter or unnecessary files.
Doesn't guarantee improved performance.
Requires a reliable backup to prevent data loss.
Limited customization options compared to a clean install.

Conclusion

Today we have explored several ways of reinstalling MacOS. This could be either a system reset or a complete reinstallation.

The installation process is pretty easy and can be performed by users who don’t possess any advanced skills as long as they follow instructions for each step. Always remember to back up your stuff before you proceed with system reinstallation or reset. This may help you to avoid losing important files.

Clean system installation can help to fix various issues in the operation of your Mac, improve its performance and provide a fresh and clean system to work with. However, before you proceed with system installation, it is recommended to clean it first: this might help to fix the problem.