Reinstall Mojave From Catalina

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After installing Mojave I figured I could run the migration assistant to pull all of the data from my Time Machine backup into the latest copy of Mojave. This approach mostly worked until I started browsing the web. The migration assistant pulled over the Catalina version of Safari which would not run on Mojave. Reinstall macOS. Select Reinstall macOS from the utilities window in macOS Recovery, then click Continue and follow the onscreen instructions. Follow these guidelines during installation: If the installer asks to unlock your disk, enter the password you use to log in to your Mac. If the installer doesn't see your disk, or it says that it can't. Installing iShowU Audio Capture on Mojave/Catalina. Download the iShowU Audio Capture installer. Once the download has finished, find the installer - it should be in your Downloads folder. Double click to open the package, and run the installer. Press the Continue button. You installed Apple’s new MacOS Catalina on your Mac, but you might be having issues with the latest version. Unfortunately, you can’t simply revert to Mojave. The downgrade requires wiping your.

If you have installed Big Sur, Catalina, Mojave or earlier versions, you may have to reinstall macOS for following reasons:

  • Reinstall When There is New macOS Version Available

Apple keeps working constantly to fix bugs, make performance tweaks, add new features or enhance coding. Therefore, doubtless, there will be new versions of macOS available to upgrade and reinstall.

  • Your Mac is Running Slow

As we all know, for no specific reason, system reinstallation can magically solve a slow Mac in most cases.

  • 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, like FaceTime won't work, Contacts or Calendar shows a delay or mess, blue teeth or WiFi won't connect…Then, you have a good reason to reinstall macOS.

  • 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 macOS as well.

Reinstall mojave from catalina

It is not complicate to reinstall macOS Big Sur or Catalina, but if you want to reinstall macOS without losing data, there are 3 steps you must follow.

Recover Files after macOS Reinstall

  • Recover data lost due to macOS reinstallation, upgrade, downgrade
  • Recover data lost due to accident deletion, formatting, etc.
  • Restore data from both internal and external storage device
  • Recover videos, audios, images, documents, and other 200+ files
  • 5 recovery modes to find files back easily
  • High recovery rate
  • Support Big Sur, Catalina, Mojave and earlier
Free Download

3 Steps to Reinstall macOS Big Sur or Catalina without Losing Data

We all save tons of data on our Mac, so when we decide to reinstall macOS Big Sur/Catalina, the top concern always goes to “will I lost everything if I reinstall macOS”. In fact, reinstallation of macOS doesn’t necessarily cause lost data, it just create a new copy, 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 macOS reinstallation without losing data.

Step 1. Prepare Your Mac for Reinstallation.

  • Make enough room for Big Sur or Catalina reinstallation, at least 36GB, 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.
  • Check drive conditions. Open Disk Utility and perform the Frist Aid on your hard drive where to reinstall the macOS to make sure your drive is in good condition for reinstallation.

Step 2. Backup All Your Files for macOS Install (Crucial)

Backup is an indispensable step involved in the macOS 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”.
  2. Click “Select Backup Disk” to choose an external hard drive to back up the files.
  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.

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.
Reinstall mojave not catalina

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.
  2. Click the “Options” button for “iCloud”, and check the box before “Desktop and Documents Folders”, then click on “Done”.

Most of our mac users prefer to backup all files but apps. So, to save you from troubles of lost data due to macOS 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 Big Sur or Catalina without Losing Data.

Option #1: Reinstall macOS without Losing Data From Internet Recovery

  1. Click the Apple icon>Restart.
  2. Hold down the key combination: Command+R, you will see the Apple logo.
  3. Then choose “Reinstall macOS Big Sur” from utilities window and click “Continue”.
  4. Select your hard drive, click “Install” and wait for end of reinstallation.

Option #2 Reinstall macOS without Losing Data From USB

  1. Download the macOS Big Sur install from Mac App Store onto your Mac;
  2. Then connect the USB flash drive to your Mac;
  3. Open Disk Utility program on your Mac, choose the USB flash drive and click Erase to have a clean drive for the reinstallation;
  4. Open Terminal, copy and paste sudo /Applications/Install macOS Big Sur.app/Contents/Resources/createinstallmedia;
  5. Then add the volume of usb flash drive: --volume /Volumes/MyVolume, replace MyVolume with your usb flash drive name, mine is Untitled;
  6. Press Enter, input password and wait for the process to finish;
  7. Quit Terminal, restart your Mac, hold Command+R when starting Mac until you see the apple logo;
  8. Login into your Mac with password, go to the menu bar>Utilities>Startup Security Utility, enter password again;
  9. Choose Medium Security under Secure Boot and allow booting from external media;
  10. Restart your Mac, in the same time, hold the Option key;
  11. Choose Install macOS Big Sur, click Next and input password, choose Install macOS, continue to finish mac reinstallation from usb.

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What if You Lost Data After macOS Big Sur 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 Cisdem Data Recovery to Recover Data

In the case 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.

Main Features of Cisdem Data Recovery

  • Recover files lost due to OS reinstallation, upgrade, downgrade;
  • Recover deleted, formatted and lost files;
  • Restore files from internal and external hard drive, USB, SD Card, flash drive, etc.;
  • Restore videos, audios, images, documents, archives, 200+ types;
  • 5 recovery modes: Basic, External Drive, Formatted Drive, Trash, Advanced;
  • Preview files before recovery;
  • Fast scanning and recovery;

Steps to Recover Lost Data after MacOS 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”.
  3. Select the hard drive where you originally stored the files on mac. Then click “Scan”.
  4. Check and preview files found by Cisdem Data Recovery.
  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.

Method 2: Use Time Machine to Recover Data with Backup

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.
  • Step3. Find the deleted files, then click “Restore” to recover the lost data caused by reinstallation.

Conclusion

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

Catalina

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

I’ve been driving myself insane over the past few weeks months shopping for a new computer. So many options, so many new features. (Such high prices!)

During this search, I decided to take advantage of Apple’s 14-day trial period and test out a few of Apple’s newest MacBook Pros. Both of them were seriously impressive machines. If it was my first Apple computer I’d probably go ahead and buy them. But, they weren’t my first Apple machines. These computers were running Catalina which I was unfamiliar with. Due to changes in the operating system, an insignificant number of fonts, files, and several programs I use a few times a year were not recognized and couldn’t be opened. This was too much for me to deal with in those 14-days, so I decided to return the computers and keep exploring my options.
Before returning them to Apple, I needed to wipe the drive clean. Apple has 3 articles outlined on their site on how to do this.
What to do before you sell, give away, or trade in your Mac
How to erase a disk for Mac
About macOS Recovery
Maybe because the instructions are split across 3 different web pages, I got confused and missed a step, wasted time, and finally ended up calling into their help desk.

So for my own reference, let me talk you through my experience. If you need to do this for a computer running Catalina, maybe my experience will help fill in some blanks.

Catalina

Quick Add: I tested 2 other computers running Mojave and Sierra, since originally writing these steps. I followed these steps each time. I made a few updates where relevant based on those experiences, including a computer with a 3rd-party SSD installed.

Primary Steps to Wiping a Macintosh Hard Drive Running Catalina

How Do I Reinstall Macos Mojave From 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.

1. Create a backup. In my case, since I had transferred files from a backup, I didn’t need this. But if this is your first computer, you should.
2. Sign out of iCloud. This worked exactly as Apple describes it for Catalina. iCloud is available in System Preferences. I think it did require my Apple ID or my computer’s administrator password. (Actually for one of these computers, I didn’t fully log out. Thankfully, you can log into iCloud via another computer and log out that way.)

Update: In 2 cases, I had devices that remained connect to my AppleID despite signing out of iCloud out on the computer. Neither of these devices were running Catalina. I recommend that after you sign out of your computer, visit your Apple ID and check that the device has been removed from your account. You may also need to check your other devices, too (iPhone, iPad, etc). Disappointing this isn’t part of Apple’s instructions.

3. Sign out of iMessage. I didn’t use iMessage, so I couldn’t sign out. (Or maybe that’s why I was still logged in!) In fact, this step was the first time I’d even opened iMessage, which I don’t use. I did see messages from years ago that got transferred over from my original backup file.
4. Reset NVRAM. This is supposed to delete security settings, like perhaps the fingerprint authorization if you’re using a laptop with the TouchBar.

  • In order to reset NVRAM, you shut down your computer. When you restart, immediately press and hold Option+Command+P+R for about 20 seconds. There’s no real indication anything is happening. I ended up trying this about 3 times before deciding I was done.
  • What should happen is you shut down, press Power, the Apple logo appears. Press and hold the keys, the Apple logo goes away. When you let go after 20-30 seconds, it comes back.
  • Note: I tried this on a 2019 iMac running Mojave. The Apple logo went away, then came back on its own after a few seconds. On a MacBook Pro running Sierra, I heard the restart repeating about 3 times until I let go.

5. Unpair Bluetooth devices(as needed). No pairs for me.

6. Erase your hard drive and reinstall macOS. This is the hard part. Apple actually explains this in more detail on another page, which might be why it’s a little confusing.

This section was tricky for me because I mistakenly assumed the options for erasing a drive on Catalina were the same as my other computer running El Capitan. No! Well, I ended up consulting a few sources because none were absolutely clear.

Here are the 13 steps for fully erasing the hard drive.

13 Steps to Erase the Hard Drive (or Step 7 continued):

7.1 Shut down the computer.

7.2 Restart while pressing and holding Command + R. Don’t let go until you see the MacOS Utilities menu. (Actually, you can let go once you see the Apple logo. A language menu will show first.) This boots the computer in Disk Recovery. There will be a few options in Disk Recovery:

  • Restore from a Time Machine backup
  • Disk Utility [This is what you want]
  • Reinstall MacOS
  • Get help online (opens in a Safari, only)

7.3 Select Disk Utility. Once you get in here, you’ll see the same Disk Utility as if you’d searched in System Preferences.

7.4 Select View All. This is a critical step!! The drives you need for Catalina (as well as Mojave) are hidden by default. Make sure you complete this step by selecting View All to view all hidden drives.

How To Reinstall Mojave From Catalina

7.5 Select your drive. Once you’re viewing the full list of drives, after selecting View All, you should select the very first one at the top of the list. You may have given it a new name, but this is your main drive.

7.6 Select Erase to view erase options. After selecting your drive, the options at the top of the window should include Erase, which should not be inactive at this point. Select Erase to open the menu options for your drive (see image).

  • Regarding drive naming options: When I managed to complete this correctly, I was on the phone with an Apple support technician. She told me I did NOT need to name the drive — e.g., ‘Untitled’ was fine. So although the image above clearly shows someone naming the drive Apple SSD, I did not. Howeverattempting this on that iMac with a 3rd-party SSD installed, it didn’t like ‘Untitled’ so I used the name of the 3rd-party drive.
  • The drive format: Apple’s instructions essentially say that whatever pops up as the default option is fine to stick with.

7.7 Erase the drive. Once all options have been made, click Erase. Deleting only takes a few moments. You’ll get a confirmation that the erase was successful.

7.8 Quit Disk Utility. After the drive is erased, you’re done. Close out of Disk Utility. You’ll return to the previous screen, Disk Recovery.

7.9 Back in Disk Recovery, select Reinstall MacOS.

7.10 Select ‘Untitled’ during the reinstallation process. After 7.9, the installation process will ask where to install MacOS. Choose the drive that was erased. It will be named ‘Untitled’ or whatever name you gave it.

7.11 Wait while your computer installs MacOS. You’ll need to be connected to the internet. If not, you’ll get prompted to select a network and password if you don’t have a wired connection. This step will take about 45 minutes to one hour, even though it starts out saying something like 8 minutes.

Notes on 7.11:

  • If you did not erase the drive correctly, what happens is you’ll get to almost the end…and then you’ll get a message telling you that Mac OS cannot be installed. This is because the OS is still installed and it can’t be overwritten in this way.
  • I’ll also note that you cannot install an operating system your computer didn’t come with using these instructions. You cannot try to rollback to Mojave from Catalina, for instance, using this method.
  • These notes are written for Catalina (and other computers that have not had their operating systems upgraded). I do not know what happens to computers that have been upgraded. It’s possible reinstalling MacOS installs the OS originally installed on the computer, or it could be the last OS installed.
Reinstall

7.12 Computer restarts in welcome, setup mode. Once the operating system has been properly installed, the computer will automatically re/start in the welcoming start-up screens that you encounter on a brand new computer. Continue as necessary.

7.13 If you do not want to continue, press Command + Q to quit the start-up and the computer will shut down. If you have a laptop, it will power up automatically when the lid is opened.

Now you’re completely done! Hope that was helpful.

Extra resources:

  • Searching further, I found instructions from MacWorld that specifically references Catalina. How to wipe and factory-reset a Mac: the method has changed in Catalina. These instructions were thorough in some ways, but also not correct in others.
  • To gain more courage in this process, I watched this video from AppleInsider. It is NOT tailored for Catalina. But it was helpful from an overall process perspective. I’ve queued it to start at Disk Recovery.

Extra Tips:

  • Keep the computer plugged in to power.
  • Try not to let your computer go to sleep during Reinstall MacOS.
  • Use another computer to read instructions vs your phone. It’s easier to search and switch between windows, if you’re not using instructions that are all on one page.
  • Back up your data ahead of time, if you intend to keep the files.

Using My Own Instructions to Wipe an iMac Running Mojave

As mentioned, I’ve been on the hunt for a new computer for a few months. I’ve tried 3 different Macs — 2 laptops and an iMac, as the title states. The 2 laptops I bought from Apple’s refurbished store. The iMac was purchased from Other World Computing.

OWC conveyed that wiping the computer was not necessary, but I chose to do it anyway. I referenced my own list above. I only have a few tips to add.

  • Definitely check iMessage to sign out. I hadn’t opened it before, and assumed that I hadn’t been logged in. Turns out I still needed to sign out.
  • Confirm sign outs via iCloud. Use iCloud to confirm your account has been fully signed out from all computers/devices that you don’t want associated with your account.
  • Check that if any licenses or subscriptions need to be deactivated. For instance, I had purchased a second copy of CleanMy Mac when I had the laptops running Catalina. In order to use the license on another computer, it had to be deactivated via the CleanMyMac website. It doesn’t matter that the drive was wiped. In addition, not only could Catalina not run older Adobe software, it also couldn’t run the uninstallers.
  • Stick with the default drive format. I was also not exactly sure about the drive format. So I checked the Apple website again, and just stuck with the default choice: “Format: Choose APFS or Mac OS Extended (Journaled). Disk Utility shows a compatible format by default.”

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