Updating macOS can be a real chore sometimes, especially if you get stuck in an update loop because there isn’t enough free space. Some users started the update but found themselves stuck in this “boot loop” after it failed, returning to the update installer page every time their Mac booted up again.
If there isn’t enough free space on your Mac, usually you get an alert before you start the update. But if your update failed during installation, or if that alert failed to read your storage properly, you might find yourself with problems.
In this post, we’ve explained a few different ways to break out of the macOS update loop and make sure you have enough free space on your Mac.
- 1 Why do I need free space to update macOS?
- 2 How do I create more free space from a macOS update loop?
- 3 Tips for creating more free space on your Mac
- PSA: macOS Catalina will kill your 32-bit apps — here’s what you should know
- How to use the new storage optimization features in macOS Sierra
- MacBook will not start up after macOS update, how-to fix
- How to create a macOS Catalina USB installer
- macOS could not be installed, how-to fix
Why do I need free space to update macOS?
It’s not immediately obvious why your Mac needs free space to update itself anyway. Especially after you already made enough space to download the update. But in fact, the macOS update installer needs extra room to work in.
As the update installs, it copies files and expands folders, taking up much more space than it needed to download. In fact, you often need as much as 20 GB of free storage on your Mac to update the operating software on it.
Without that space, the macOS update installer can’t complete all of its tasks, and the update fails.
How much free storage do I need to update macOS?
Apple lists storage space recommendations for macOS updates on its website. Click here to take a look at that page, typically Apple suggests you need around 20 GB of free space.
We advise you to give your Mac 1.5x Apple’s recommended storage requirement for an update. This should avoid the risk of getting stuck in a macOS update loop.
Regardless of whether you’re updating your Mac, try to keep at least 10% of your hard drive empty. This is common advice to help your computer run smoothly.
How do I create more free space from a macOS update loop?
If you can, reboot your Mac and sign in. Then free up more space by deleting large files or moving them to an external hard drive. We’ve included more space-saving tips at the bottom of this post.
But if you can’t log in to your Mac — which is probably the case if you’re reading this post — follow the troubleshooting steps below to break out of the macOS update loop or free up space from within the macOS installer.
Step 1. Change your startup disk
Move your mouse to the top-left corner of the screen, you should see a menu bar appear. Go to > Startup Disk… and select your Mac’s hard drive, which is usually called ‘Macintosh HD.’
Click Restart and wait for your Mac to reboot. It should boot up normally, breaking you out of the macOS update loop. Now you can follow these tips to free up enough space for the macOS update.
What if I can’t see a menu bar?
If there’s no menu bar or no option to choose your startup disk, reboot your Mac into Recovery Mode. Do this by holding the command+R keys while powering your Mac on.
From Recovery Mode you should be able to follow the instructions above to choose your startup disk.
What if I can’t choose my startup disk?
If the Startup Disk window doesn’t show your Mac’s hard drive, follow the instructions below to repair your drive using Disk Utility. Then try choosing your startup disk again.
Step 2. Repair your hard drive using Disk Utility
Small problems with your drive might be the reason your macOS update failed, they might also be the reason you can’t select your Mac’s hard drive as the startup disk. Fortunately, they’re easy to repair using Disk Utility.
You should be able to open the Disk Utility application from the Utilities option in the menu bar. If you can’t see a menu bar, follow these instructions to boot your Mac into Recovery Mode.
In Disk Utility, select your Mac’s hard drive from the sidebar, it’s usually called ‘Macintosh HD.’ Make sure you select the parent level drive, which may have a different name. Now click the First Aid button and Run first aid on the drive.
This checks your hard drive for errors and repairs any it finds. Reboot your Mac when it finishes, if you return to the macOS update installer again, repeat these instructions to choose your startup disk.
Step 3. Erase your hard drive, if you have a backup
If you have a recent backup of your Mac — or if you don’t mind losing all the content and data on it — the next step is to erase your hard drive completely. If you don’t want to erase your Mac, click here to skip to the final step instead.
After erasing your Mac, you should definitely have enough free space to update macOS, at which point you can restore your backup.
How do I erase the hard drive on my Mac?
- Erasing your hard drive permanently deletes all your content — films, photos, documents, etc. — do not do it unless you have a backup.
- Boot your Mac into Recovery Mode by holding the command+R keys while it powers on.
- From the menu bar, go to Utilities > Disk Utility.
- Select your Mac’s hard drive from the sidebar.
- Click the Erase button and confirm you want to erase your Mac.
How do I update macOS after erasing my hard drive?
- Boot your Mac into an alternate version of Recovery Mode by holding OPTION+command+R while it powers on.
- Click ‘Reinstall macOS’ to update your Mac to the latest version of macOS compatible with your machine.
How do I recover my Time Machine backup?
- After completing the macOS update, boot your Mac into Recovery Mode a final time by holding the command+R keys while it powers on.
- Click ‘Restore from Time Machine Backup.’
- Connect your external backup drive and select the most recent backup.
Step 4. Create enough free space for the macOS update using Terminal
If you don’t have a backup and you can’t change your startup disk, your last option is to remove data from your Mac using Terminal. This requires you to enter terminal commands to navigate your hard drive and choose which files to remove. We’ve explained exactly what to do below.
Make sure you enter each command exactly as it’s written below, including punctuation and whitespaces.
How do I open Terminal from the macOS update installer?
- Boot your Mac into Recovery Mode by holding the command+R keys while it powers on.
- From the menu bar, go to Utilities > Terminal.
How do I navigate using Terminal?
You only need to know the following three commands to navigate using Terminal:
- Print Working Directory (pwd)
- List (ls)
- and Change Directory (cd).
Print Working Directory (pwd): Displays your current position in the hard drive, shown as a file path.
List (ls): Displays a list of all the files and folders in your current position.
Change Directory (cd): Allows you to move to a different position in the hard drive, by typing the file path you want to go to.
When typing a file path, insert a backslash (\) before a space. You can also use a period (.) as a shortcut for typing your current location. And finally, after you start typing, you can use Tab to cycle through autocomplete options.
How do I remove files using Terminal?
When you locate a file you want to delete, there is only one command you need to use to delete it:
- Remove (rm).
Remove (rm): Use this command, followed by a filename in your current location to immediately and permanently delete it. Be careful to type the filename correctly, including its file type, to ensure you don’t delete the wrong file.
How do I find large files using Terminal?
If you’re struggling to find large files you can delete to make enough free space for the macOS update, use the command below to see a list of every file on your Mac larger than 500 MB:
find / -size +500000 -print
You can then use the commands above to navigate to and remove those files.
Tips for creating more free space on your Mac
When you’re able to log into your Mac again, use these tips to create enough free space for future macOS updates and keep your storage use to a minimum.
1. Use iCloud Drive to optimize storage
iCloud presents the simplest way to free up space on your Mac. If you subscribe to extra iCloud storage, use iCloud Drive to upload your documents to the cloud.
Then go to your iCloud preferences and turn on Optimize Storage for iCloud Drive. This automatically removes old files from your hard drive — keeping them on iCloud Drive — to create free space on your Mac.
2. Move data to an external hard drive
If you have a lot of files or folders you don’t need all the time — like work archives, or movie collections — move all that data off your Mac and onto an external hard drive.
You can do this using drag and drop in Finder, then be sure to delete those files from your Mac when they’re safely stored to an external drive.
3. Don’t forget to empty the Trash
After you delete files, don’t forget to empty the Trash. Otherwise they still take up space on your hard drive. To do this, control-click on the Trash can in the dock and select ‘Empty Trash.’
Let us know your own space-saving tips in the comments below. And be sure to tell us if you’re still stuck in a boot loop trying to update macOS, we’ll do whatever we can to help you out.
Dan is a freelance writer based in South West England.
He spent two years supervising repairs as a Genius Admin for Apple Retail and uses that knowledge to keep our troubleshooting guides up to date.
Long before that, Dan turned to Apple products from a musical background. Having owned iPods for years, he bought a MacBook to learn sound recording and production. It was using those skills that he gained a first-class Bachelor of Science in Sound Technology.