Download macOS Catalina 10.15.2 Combo Update The Combo Update is a fuller install, as opposed to an incremental 'delta' update, so it should overwrite any files that are damaged or missing. It does not matter if you have applied it before. 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. Access System Preferences Startup Disk and choose your Catalina installer. Restart your Mac and hold Command-R. Connect your bootable USB. In the macOS Utilities window, click Reinstall a new copy of macOS. Click Continue and agree to the terms and conditions. Select your startup drive and click Install. On an Intel-based Mac: Choose Apple menu Restart, then immediately press and hold Command-R. In the Recovery app window, select Disk Utility, then click Continue. In Disk Utility, select the volume you want to erase in the sidebar, then click Erase in the toolbar. Type a name for the volume in the Name field, click the Format pop-up menu.

1. Reinstall Mac Os Catalina From Big Sur
2. Reinstall Mac Os Catalina
3. Restore Mac Os Catalina To Factory Settings

Easy way to Clean Install mac OS Catalina

macOS Catalina is Apple’s shiny new operating system for the Mac and it’s got a ton of great features and improvements. You’re probably keen to get started and install it straight away. Before you do, consider whether you want to install it over the top of your current OS, or as a completely clean install of macOS Catalina. The benefits of the latter are that it will be like a completely new Mac, with all your settings wiped out, and junk files gone. It should make your Mac run faster. The rest of this article will explain how to clean install macOS Catalina.

Before the clean installation of macOS 10.15 Catalina it’s recommended that you first delete junk and dusty files from the current macOS. There are many free and paid tools to clean junk but the quickest option is to run CleanMyMac X. You can expect to free up tens of gigabytes of space, including old apps, and their leftovers.

Here’s how it works.

1. Download and install CleanMyMac — try a free edition of the app here
2. Choose the System Junk tool.
3. Press Scan.
4. When it’s finished either press Remove to get rid of all the files it recommends, or choose Review to look through what it’s found and decide for yourself what to delete and what to keep.

Backup your Mac

I can’t stress how important this is. You must backup your Mac before you do anything else. You’re going to be erasing your startup drive completely, so you need a complete backup of everything. You can use Time Machine, another backup app, or a cloning tool. Just make sure you have a complete, preferably bootable, copy of your current installation.

You should also make notes of settings for apps you use regularly – screen grabbing them is a good way to do that. And you should make sure you have a copy of any licence codes that you’ll need when you reinstall applications. You can use Apple’s Notes app to make notes, as long as you sync them with iCloud.

Create a bootable installer of macOS Catalina

If you’re reading this after Catalina ships, you can download it from the Mac App Store and then choose Quit when the installation starts. If you’re clean installing the beta (and, by the way, that’s not something I would recommend. It’s much better to create a dual boot system when you run the beta.

1. Grab a USB stick with a capacity of at least 16GB, or an external hard drive or USB.
2. Go to Applications>Utilities and launch Disk Utility.
3. Launch Disk Utilities and Erase the Drive or USB stick, formatting it as Mac OS Extended (Journaled) or APFS and selecting GUID partition map if a selection is available.
4. The easiest method for creating a bootable installer is to use DiskMaker X. However, if you’re comfortable using Terminal, you can do it like this:
   1. Launch Terminal from Applications>Utilities
   2. Type: sudo /Applications/Install macOS Catalina Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install macOS Catalina Beta.app where ‘Untitled’ is the name of your USB stick or external hard drive
   3. Press Return and wait for the word Done to appear in Terminal.

Once you see ‘Done’ in Terminal you can quit it. Your USB stick or external hard drive is now a bootable Catalina installer, so keep it safe. Now, it’s time to clean install macOS Catalina.

How to Clean install macOS Catalina

Now you've made a backup and created a bootable installer, it's time to actually install the new macOS. Follow these easy steps to clean install macOS Catalina on your Mac.

1. Plug your USB stick or external hard drive into your Mac, if it’s not plugged in already.
2. Restart your Mac while holding down the Option key.
3. When you see the options for booting appear on screen, choose the installer disk you just created.
4. When you see the macOS Utilities screen appear, choose Disk Utility
5. When Disk Utility launches, choose the Eras tab then select your startup volume (probably called Macintosh HD).
6. Give your startup disk a name, then choose a format. If you have a recent Mac with an SSD startup disk, select APFS. If you have an older Mac with a mechanical hard drive or Fusion Drive, choose whichever one you want to use.
7. Choose Erase.
8. When Disk Utility has finished erasing the disk, quit it to return to the macOS Utilities screen.
9. Choose Install macOS.
10. Press Continue and choose the drive you just erased and re-formatted as the destination.
11. MacOS Catalina will start to install.
12. When it’s finished, your Mac will restart and it will look like a brand new Mac. Go through the set-up process to set up a user account, add your wifi network, choose a language, and log in to iCloud.

Once you’ve set up your Mac, you can eject the installer disk and remove it. Remember to keep it safe. You can now restore files you backed up earlier from Time Machine or whichever backup tool you used. Remember to restore files and folders individually, don’t, for example, restore your entire user directory otherwise you’ll copy back all the junk files you just got rid of. Reinstall applications and go through them adding license details where necessary. Check that everything works as you expect it to and use the screen shots you made earlier to configure settings.

There are lots of good reasons why you might want to clean install macOS Catalina, but the most important one is that it should make your Mac feel like new and keep it running smoothly. For ultimate Mac refresh you can also download CleanMyMac X and play with its cleanup tools. Getting rid of old junk feels great.

Downgrade Catalina to Mojave

If you’ve installed macOS Catalina and run into problems with some of your apps, or you’ve just decided that you don’t like it as much as Mojave, the good news is that you can downgrade back to the previous version of macOS. The bad news is that it’s a lengthy process with several steps. Read on to find out how to do it.

1. Back up your Mac

You should have backed up your Mac before you upgraded to Catalina, as you should before you perform any major upgrade or make any significant change to your Mac. However, the files you’ve been working on since you upgraded won’t be up to date on that backup. So, you should copy those files to an external disk, or a cloud storage service like Dropbox or iCloud Drive so you can retrieve them easily when you downgrade. We’re going to completely erase your Mac’s startup disk, so it’s important to copy anything you need now.

Before you backup, however, you should take steps to remove the junk and clutter from your Mac. There’s no point in backing up all the clutter along with the files you really need. To do that, I recommend CleanMyMac X. It’s the easiest way to clear out the clutter on your Mac. Here are just a few things it can do:

• Delete years worth of system junk
• Find hidden apps and folders
• Neutralize Mac-specific malware, like key loggers
• Manage hung apps and heavy CPU consumers
• Update all your software to the latest-supported versions

As you can see, CleanMyMac X does a lot more than just clear out junk files before you backup your Mac. It’s well-worth keeping it on your Mac and using regularly to keep your Mac running smoothly.

2. Save your passwords

When you downgrade mac OS Catalina, you’ll delete everything from your hard drive, including licence keys and settings. So, in addition to making sure you copy all the files that have changed since you last backed up, you should make a note of those. If you use a password manager that syncs with other devices and allows you to store licence codes and encrypted notes, you could use that. If not, any app that allows you to sync encrypted notes will do. Or you can use Apple’s Notes app. It’s also a good idea to take screen grabs of settings to make it easier to restore them later. Remember to copy the grabs to a cloud storage service or an external disk.

3. Create a bootable installer of macOS Mojave

Note, you can skip this step if your Mac shipped with macOS Mojave or if you made a backup with Time Machine before you upgraded to Catalina.

1. If you’re reading this before macOS Catalina ships, you can go to the App Store and search for Mojave, then download it. If it tries to install when it’s finished downloading, quite the installer.
2. If you’re reading this after Catalina ships, you can download Mojave ‎here, but only on a Mac that’s not already running Mojave. When you click that link, Software Update will launch and start to download Mojave. When it’s finished, quit Software Update.
3. Grab a USB stick with 16GB capacity or an external hard drive or SSD and plug it in to your Mac.
4. Launch Disk Utilities and Erase the Drive or USB stick, formatting it as Mac OS Extended (Journaled) and selecting GUID partition map if a selection is available.
5. The easiest way to create a bootable installer is to use DiskMaker X. However, you can also do it in Terminal like this:

• Launch Terminal from Applications - Utilities
• Type: sudo /Applications/Install macOS Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled where ‘Untitled’ is the name of your USB stick or external hard drive
• Press Return and wait for the word Done to appear in Terminal.

Whichever method you used, you should now have a bootable macOS Mojave installer. Keep it safe.

4. Uninstall macOS Catalina

1. Make sure your Mac is connected to the internet.
2. Click on the Apple menu and choose Restart.
3. Hold down Command+R to boot into Recovery mode.
4. Choose Disk Utility in the macOS Utilities window
5. Select your startup disk
6. Choose Erase
7. Quit Disk Utility

How to downgrade Catalina to Mojave if your Mac shipped with Mojave

1. Once you’ve erased your startup disk and quit Disk Utility as described above, choose Reinstall macOS from macOS Utilities.
2. Press Continue.

How to rollback from Catalina using a Time Machine backup

If you backed up your Mac with Time Machine before you installed Catalina, you don’t need to create a bootable installer – you can just reinstall Mojave from your Time Machine backup. Make sure it’s plugged in if it’s an external disk. If it’s a network disk, make sure you’re connected to the network.

• Once you’ve erased your start up disk as described above, choose Restore from Time Machine backup in the macOS Utilities window.
• If your backup is on an external disk, select it. If it’s on a network disk, select it and choose Connect to Remote Disk.
• Type in your username and password for the remote disk if necessary.
• Select the data and time of the backup you want to restore from.
• Follow the onscreen instructions.

5. Install Mojave using a bootable installer

If you have a Mac that didn’t ship with Mojave and you don’t use Time Machine to backup, you’ll need to reinstall Mojave from the bootable installer we created earlier.

1. Plug in the installer disk.
2. Go to the Apple menu and choose restart, then hold down the Option key.
3. Mojave will start installing on your Mac.
4. When it’s finished, your Mac will restart and the Setup Assistant will appear
5. Follow the steps in the SetUp Assistant to set up Mojave

Restore your settings

If you have reinstalled Mojave from a bootable disk, rather than a Time Machine backup, you will need to reinstall applications and copy documents across from your backup. That’s where those notes and screen shots you made earlier come in handy!

Reinstall Mac Os Catalina From Big Sur

Once you’ve restored your settings and reinstalled all the apps you need, your Mac is ready to use again, running Mojave instead of Catalina.

Tip: If you want to roll back to an earlier version of macOS than Mojave, you can. To reinstall the OS your Mac shipped with, use the method in ‘How to downgrade if your Mac shipped with Mojave’. If you want to roll back to a version of macOS newer than the one your Mac shipped with but older than Mojave, you can download Sierra and earlier versions from the Mac App Store. Then follow from Step 3 in ‘Create a bootable installer of Mojave’.

Reinstall Mac Os Catalina

My Mac is still underperforming, what to do?

You thought that reverting to macOS Mojave would get your Mac back to norm. But if it didn’t and you still experiencing sudden freeze-ups and glitches, full disk cleanup is your answer. Probably there are too many conflicting system junk files on your drive that you need to plow through.

You don’t need a regular disk cleanup app — most of them are scam — but this tool, CleanMyMac X, is notarized by Apple, and can really do helpful optimizations on your Mac.

• Download the free edition here
• Go to Maintenance tab

Now you can perform some of the tasks suggested by the app, like running Maintenance Scripts. Also, check the System Junk tab and remove all the useless files it recommends you to delete.

Restore Mac Os Catalina To Factory Settings

As you can see, it is possible to uninstall Catalina if you decide you don’t want to continue using it. It’s essential, however, that you backup your Mac before you upgrade. And remember, before you backup, clear out the clutter with CleanMyMac X. That way you won’t use precious space on your backup drive copying over junk files.