“Your startup disk is almost full” Mac Error – How to Remove It

Today is one of those days when your computing doesn’t work as fine as usual. After starting your Mac you have encountered an extremely disturbing pop-up message that alerts you the following – “Your startup disk is almost full”

your startup disk is almost full pop-up on mac

You probably get that feeling that this is not cool. Don’t worry we prepared this guide to reveal all important details about this disturbing issue as well as several fixes that are proved to be efficient against it.

What Is a Startup Disk?

Let’s start by explaining the main term in this Mac error message. The startup disk is the hard drive that stores the operating system. Hence, it is the most important disk of all. So in the event that you encounter a pop-up that alerts “Your startup disk is almost full”, it basically means that your primary disk drive is running out of space which is very bad news.

What Does the “Startup Disk Full” Mac Error Mean?

The meaning of this message should be understood literally. What does the full error message say when it pop-ups on Mac? Here is a copy of its text:

Your startup disk is almost full.
To make more space available on your startup disk, delete some files.
Don’t warn me again about this disk.

The “Your startup disk is almost full” message means exactly what it says. Your startup disk is running out of storage and you should definitely not ignore this message. Otherwise, you may end up having even more serious issues that prevent you from using your Mac.

This error message often appears due to the fact that you are having too many files that occupy your Mac’s hard drive. This, in turn, brings the free disk space to a dangerously low level. As a result, you may not be able to start your computer or it may become sluggish due to lack of enough operative space for the operating system.

How Do I Fix and Remove “Your startup disk is almost full” Error on Mac?

First, you need to discover what is taking up all the space on your startup disk drive. To see how your space is being used follow these steps:

  • Click on the Apple Icon.
  • Select About This Mac.

About This Mac menu

  • Click Storage (or More Info).

The Storage tab will show you a graphical display of all main categories files that are stored on your drive as well as exact information about the memory size different categories took on the drive. This information may help you to determine where to start the disk cleanup process.


To remove “Your startup disk is almost full” error on Mac you should delete some files and increase the amount of free space available for your system. The options for you are the following:

    1. Remove some files manually
    2. Use a special app to find unneeded files and clean up startup disk
    3. Upload some of the biggest files to the could or a backup disk and remove them from the startup disk

Remove “Startup disk is almost full” Manually

Oftentimes, the biggest space eaters are the files contained in the category “Other”. Files there are usually caches, archives, logs, disk images, plugins, cookies, extensions and so on.

The manual process will take some time. You should be very careful while completing the manual steps because, in the event that you inadvertently delete a file that is essential for the proper operation of your system, it may crash. If you don’t feel comfortable with the manual process of fixing “Your startup disk is almost full” error, then navigate to the automatic approach.

Delete Unnecessary Apps

Probably some of the apps you installed on your Mac are no longer of use to you. Go find these apps and delete them. We recommend that you perform a complete uninstall process instead of just moving the unused apps to the Trash. Surely, the second approach will save some space and time but the first guarantees that all storage used by these apps will be cleared.

Delete Old iOS Backups

If you have the practice to back up your iPhone or iPad using iTunes on your Mac, then you may have lots of old backups that are taking storage on your startup disk. To clean all old and unnecessary backups go to iTunes and navigate to preferences. You will see all the old backups that are stored on your machine. Select and delete all older backups you don’t need. Make sure to keep the most recent one as it is still essential to have reserve copies of all files and settings on Mac. One never knows what will come next.

Lots of nasty unwanted applications are lurking on the web. A recent example is the Calendar Mac/iPhone Virus Notification type of threats. They hijack users’ devices and flood Calendar apps with intrusive annoying notifications. Sometimes the only way to get rid of such annoying apps is to reset the whole system. In such an event you will definitely need a recent backup that will restore saved data in a matter of minutes.

Clean Up Your Downloads Folder

Which is your default Download folder? Find it and make sure to revise all files stored there. The Download folder contains all files which we download from the Internet. Here’s why it can become extremely large in size over time. Cleaning up all files you downloaded from various websites and never used afterward can return some critical space for your operating system.

Get Rid of Mail Downloads

Do you know that whenever you view an email attachment, your macOS Mail app saves a copy of this attachment in a separate folder? Well, now is the time to find that folder and clean data stored in it to get rid of that nasty “Your startup disk is almost full” Mac error. Go to the Spotlight and search for Mail Downloads. You may be surprised how much data has been added there.


Empty Trash

Finally, it is time to open your Trash and clean everything you added there. Since it often takes lots of disk space you should regularly empty it. So, go clean your Trash now and free some space on the startup disk.


Remove “Startup disk is almost full” Automatically

Checking various locations on your Mac including the home, Apps, Trash, Downloads, etc. for unnecessary files or apps is a time-consuming process for sure. The good news is that there is a much faster way to reduce the amount of storage on your startup disk. By using the help of an advanced anti-malware tool with an integrated Disk Cleaner feature you can perform a disk cleanup process just in a few minutes. With only one click you will clean application caches, downloads, application logs, trash, and other obsolete files and regain valuable disk space.

Combo Cleaner offers advanced security features along with other modules that will improve your Mac’s security and protect it from viruses in the future.


Combo Cleaner

After you download and install the program, open it on your Mac and navigate to its Disk Cleaner tab. There you will find all the unnecessary items. Mark all different types of files you want to remove and click the Remove button to get rid of them.


With the help of the presented steps, you should fix the troublesome “Your startup disk is almost full” error message on Mac. If you don’t you risk that next time you power on your Mac, it won’t start at all.

Gergana Ivanova

Gergana Ivanova

Gergana has a bachelor's degree in Marketing. She has been with the STF team for five years, researching malware, reporting on the latest computer infections, and following digital marketing trends.

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