• Primary Steps to Wiping a Macintosh Hard Drive Running Catalina. These are the main steps to wiping your data from the computer. First you’ll be removing your Apple ID, then wiping security settings like your fingerprint ID. Then you’ll erase the drive and reinstall macOS. The entire process takes 1-2 hours.
• If you have a Time Machine backup saved from when your Mac was using Mojave, you can also choose to reinstall this particular backup to fully wipe out the Catalina OS.
• Easy & simple way to reinstall Mac if you are thinking about selling your computer or simply need to install a fresh copy macOS Catalina follow the tutorial.

When Disk Utility has finished erasing the disk, quit it to return to the macOS Utilities screen. Choose Install macOS. Press Continue and choose the drive you just erased and re-formatted as the destination. MacOS Catalina will start to install. When it’s finished, your Mac will restart and it will look like a brand new Mac. To reinstall macOS, including the latest Big Sur, Catalina, Mojave, without losing data, you can follow the professional guide to update the OS, which will not cause data loss in most of the case. If you still have worries, back up your Mac in advance or recover the lost files with EaseUS Data Recovery Wizard.

How to access and use the Internet Recovery mode on Mac computers?

Apple computers are well-known as stable devices with good performance and hardware specifications. The Mac operating system also includes various self-diagnosis and repair tools. Bear in mind, however, that these features might be susceptible to failure. When built-in tools or software-based solutions do not work, the last and most efficient solution is to reinstall the operating system. All modern Mac computers contain two separate methods to reinstall the operating system (by 'reinstall', we mean installation of a fresh OS X version). You can choose to install the operating system from a startup disk or via Internet Recovery.

In this article, we describe the second method: Internet Recovery to install the operating system version that came with the version of your computer. If your computer was released with OS X Mavericks, using Internet Recovery will install this particular version, while reinstallation from the recovery partition will result in a fresh version of the current operating system. Therefore, if you perform the reinstallation process via the Recovery utility, you will receive the same operating system version that existed prior to reinstallation. The Internet Recovery method is useful if you wish to downgrade the operating system. A big advantage of this method is the ability to bring back the computer to full functionality when software is corrupted. Note, however, that stable internet access is required to perform the reinstallation process via Internet Recovery. An unstable Internet connection can lead to the process crashing and no access to the computer. Therefore, you are advised to use an Ethernet network, rather than Wi-Fi. In this article, we walk through the entire Internet Recovery method.

Table of Contents:

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Requirements to access Internet Recovery Mode

Ensure that the Mac meets the minimum requirements to access Internet Recovery mode. All compatible computers are listed below. Bear in mind that some earlier versions of Apple devices might also use this feature. Apple state that Firmware updates grant access to Internet Recovery mode. If your device is older than the machines listed below, check the Apple firmware updates list here.

• MacBook Pro (13-inch, Early 2011)
• MacBook Pro (15-inch, Early 2011)
• MacBook Pro (17-inch, Early 2011)
• iMac (21.5-inch, Mid 2011)
• iMac (27-inch, Mid 2011)
• MacBook (13-inch, Mid 2010)
• MacBook Pro (13-inch, Mid 2010)
• Mac mini (Mid 2010)
• MacBook Pro (15-inch and 17-inch, Mid 2010)
• iMac (21.5-inch and 27-inch, Mid 2010)
• MacBook Air (11-inch and 13-inch, Late 2010)

If you wish to reinstall the Mac operating system, your network must use DHCP and WPA/WPA security methods. All authentication methods listed below are incompatible with macOS installation via Internet Recovery. If your network uses one of the methods listed, change the setting to a compatible configuration (at least for the purpose of the installation process).

• WEP
• WPA-Enterprise
• Certificate-based authentication / 802.1x
• Proxies (where specific proxy servers must be configured in network preferences)
• Captive Wi-Fi networks (where you click an “Agree” button to access the Internet)
• PPPoE (where there is no router handling the PPPoE connection)

Reinstall operating system by using Internet Recovery mode

When you are sure that the Mac is able to access Internet Recovery mode, there is another important task before installing the fresh operating system version. After a successful reinstallation process, the computer will contain only the default software (which is delivered with macOS). All personal data and applications that you have manually applied to the hard disk will be erased. To protect your personal data, create a backup with Time Machine or similar software. Finally, when you are ready to reinstall the operating system, click the Apple logo in the menu bar at top of the screen and select Restart or Shut Down. Once the system starts booting and you hear the startup chime, hold down the combination of Command, Option (Alt), and R.

Keep holding these keys until the animated globe appears with the message below stating 'Starting Internet Recovery' and 'This may take a while'. Note: If you are using a Mac laptop, use the built-in keyboard to access Internet Recovery Mode, since keystrokes might not register properly on external keyboards.

Next, select the Wi-Fi network. If you are not using an Ethernet network, click the drop-down menu and select the desired network. You must confirm access to a Wi-Fi network by entering the password. Then press Return on the keyboard or click the checkmark symbol on the screen to continue.

After successful authentication to achieve the network connection, the Mac will begin to download a recovery system image from Apple's servers. You will see a progress bar monitoring the status of the download. Depending on your internet connection, this process may take some time. Ensure that the computer is connected to the power adapter.

When the image is downloaded, the OS Utilities window will pop-up, giving access to the usual features, such as Restore from Time Machine Backup, Reinstall OS X, Get help online, and Disk Utility. From this point, the process will be similar to the reinstallation via recovery partition. Detailed information about how to install the macOS can be found in this article.

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:

How To Erase And Reinstall Macos Catalina

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

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:

How To Wipe And Reinstall Macos Catalina

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

Mac Catalina Install Time

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.

Mac Catalina Reinstall Software

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.