Mac Os Will Not Install

  
  1. Mac Os Catalina Will Not Install
  2. Mac Os High Sierra Will Not Install
  3. Mac Os 10.15.6 Will Not Install

Most of us are keen to update to a new version of macOS as soon as it is available. macOS Big Sur has been out since November 12, still, many users couldn't update their Macs straight away. It’s very frustrating if you see a message telling you that you don’t have enough space to install the new macOS. Don’t worry, though. There are lots of things you can do to fix it. We’ll show you what they are in this article.

When you have a compatible Mac and the macOS Catalina download completes, but there’s no prompt for the installation to continue, then search in your Mac’s application folder for a file called. Use a Mac OS X installation Disc. If you’re unable to use Internet Recovery Mode or create a bootable USB installer, you can still use a Mac OS X installation disc. These discs are available for OS X Snow Leopard, OS X Lion, and OS X Mountain Lion. If your Mac is from 2012 or earlier, there was an installation disc in the original box.

How much space do you need for Big Sur?

While the installer for Big Sur takes up less than 16GB of space, you should make sure that you have at least 20GB of free space on your startup disk before you try to download and install it. The more free space, the better. Your Mac uses disk space to store temporary files and provide storage for active apps and tasks (which is what RAM does), so you should never be running with almost no disk space left.

CleanMyMac X makes it very easy to free up disk space on your Mac by identifying junk files and allowing you to get rid of them with a click. It can also detect large and old files and show you the files taking up most space and uninstall applications.

How to free up space for macOS Big Sur?

Complete the following steps to ensure your Mac is ready to update to Big Sur.

1. Backup your Mac

Back up all files and data that are stored on your Mac. Preferably twice to different locations. While upgrading to Big Sur is safe, you never know when something might go wrong. If you use Time Machine or another backup tool, run a manual backup just before you upgrade. And, if you can, clone your startup disk to an external drive, too.

2. Free up disk space using CleanMyMac X

If you don’t already have CleanMyMac X installed, download it for free here. This tool will help you clear some space and delete large and old files quickly.

  1. Launch CleanMyMac X.
  2. Choose System Junk in the sidebar and press Scan.
  3. When it’s finished, press Clean to free up space, or Review Details to find out more.

3. Get rid of large and old files

Media files usually gobble up a large amount of disk space. And the worst thing is they are scattered around Mac’s folders, making it difficult to find and remove them. CleanMyMac X proves to be useful here:

  • Choose Large & Old files in CleanMyMac X’s sidebar.
  • Press Scan.
  • When it’s finished, use the middle column to filter files by type.
  • Check files that you want to delete.
  • Press Remove.

4. Use Apple’s built-in storage management tool

Apple has provided a method for you to manage storage by showing you what is taking up disk space and making recommendations for deleting. It’s not as quick and easy as CleanMyMac X, but it can help you save disk space. Here’s how to use it.

  1. Click on the Apple menu and choose About this Mac.
  2. Select Storage and press Manage.
  3. In the Recommendations section, review each section in turn.
  4. Now go through each of the sections in the sidebar.
  5. Delete files or take further action, depending on what you choose.

5. Delete local Time Machine snapshots

There is one other thing you can try if you keep getting a message telling you that you do not have enough space to install Big Sur. You should only try it if you are sure there is enough space on your startup disk and that the message is wrong. And it will only work if you use Time Machine to back up your Mac.

Time Machine stores local snapshots on your Mac. Your Mac is supposed to count the space used by snapshots as free space, which is why it looks like you have enough space for the installation.

However, it seems that the installer may not realize the space is free. The solution is to delete the snapshots. This won’t remove backups on your backup disk, just snapshots on your Mac.


Open Time Machine from System Preferences. Uncheck Back Up Automatically and wait some time till Time Machine deletes snapshots. Then you can turn Time Machine back on.

If you’re familiar with Terminal, you can try deleting local snapshots manually.

  1. Go to Applications > Utilities and launch Terminal.
  2. Type: tmutil listlocalsnapshots /
  3. You will see a list of snapshots that look like this: com.apple.TimeMachine.2020-10–09-002010.local
  4. To delete a snapshot, type: sudo tmutil deletelocalsnapshots
  5. Then type the date part of the snapshot name. For example: sudo tmutil deletelocalsnapshots 2020-10–09-002010
  6. Type Return and repeat for each snapshot you want to delete.

Hopefully, this helped you free up some space and update your Mac to the latest OS. If you're just preparing your Mac for the upgrade, don't forget to back up your data before you start clearing space. So you won't be afraid of losing anything important.

These advanced steps are primarily for system administrators and others who are familiar with the command line. You don't need a bootable installer to upgrade macOS or reinstall macOS, but it can be useful when you want to install on multiple computers without downloading the installer each time.

What you need to create a bootable installer

  • A USB flash drive or other secondary volume formatted as Mac OS Extended, with at least 14GB of available storage
  • A downloaded installer for macOS Big Sur, Catalina, Mojave, High Sierra, or El Capitan

Download macOS

  • Download: macOS Big Sur, macOS Catalina, macOS Mojave, or macOS High Sierra
    These download to your Applications folder as an app named Install macOS [version name]. If the installer opens after downloading, quit it without continuing installation. To get the correct installer, download from a Mac that is using macOS Sierra 10.12.5 or later, or El Capitan 10.11.6. Enterprise administrators, please download from Apple, not a locally hosted software-update server.
  • Download: OS X El Capitan
    This downloads as a disk image named InstallMacOSX.dmg. On a Mac that is compatible with El Capitan, open the disk image and run the installer within, named InstallMacOSX.pkg. It installs an app named Install OS X El Capitan into your Applications folder. You will create the bootable installer from this app, not from the disk image or .pkg installer.

Use the 'createinstallmedia' command in Terminal

  1. Connect the USB flash drive or other volume that you're using for the bootable installer.
  2. Open Terminal, which is in the Utilities folder of your Applications folder.
  3. Type or paste one of the following commands in Terminal. These assume that the installer is in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you're using. If it has a different name, replace MyVolume in these commands with the name of your volume.

Big Sur:*

Catalina:*

Mojave:*

High Sierra:*

El Capitan:

* If your Mac is using macOS Sierra or earlier, include the --applicationpath argument and installer path, similar to the way this is done in the command for El Capitan.


After typing the command:

Mac Os Catalina Will Not Install

Install
  1. Press Return to enter the command.
  2. When prompted, type your administrator password and press Return again. Terminal doesn't show any characters as you type your password.
  3. When prompted, type Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the volume is erased.
  4. After the volume is erased, you may see an alert that Terminal would like to access files on a removable volume. Click OK to allow the copy to proceed.
  5. When Terminal says that it's done, the volume will have the same name as the installer you downloaded, such as Install macOS Big Sur. You can now quit Terminal and eject the volume.

Use the bootable installer

Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:

Apple silicon

  1. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
  2. Turn on your Mac and continue to hold the power button until you see the startup options window, which shows your bootable volumes.
  3. Select the volume containing the bootable installer, then click Continue.
  4. When the macOS installer opens, follow the onscreen instructions.

Intel processor

Mac Os High Sierra Will Not Install

  1. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
  2. Press and hold the Option (Alt) ⌥ key immediately after turning on or restarting your Mac.
  3. Release the Option key when you see a dark screen showing your bootable volumes.
  4. Select the volume containing the bootable installer. Then click the up arrow or press Return.
    If you can't start up from the bootable installer, make sure that the External Boot setting in Startup Security Utility is set to allow booting from external media.
  5. Choose your language, if prompted.
  6. Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions.

Learn more

A bootable installer doesn't download macOS from the internet, but it does require an internet connection to get firmware and other information specific to the Mac model.

Mac Os 10.15.6 Will Not Install

For information about the createinstallmedia command and the arguments you can use with it, make sure that the macOS installer is in your Applications folder, then enter the appropriate path in Terminal: