Disk Space

That means you have no free space because you may have stored too much on the disk. Do not save any more files on the disk until you get this problem straightened out or you could corrupt the disk and lose everything.

How to Free Up Space on The Hard Drive

1. You can remove data from your Home folder except for the /Home/Library/ folder.
2. Visit The XLab FAQs and read the FAQ on freeing up space on your hard drive.
3. Also, see Freeing space on your Mac OS X startup disk.
4. What is 'Other' and 'Purgeable' in About This Mac?
5. Files That Make Up the 'Other' Storage Category, and How to Remove Them
6. Free up storage space on your Mac.
7. See Where did my Disk Space go?.
8. Be sure to Empty the Trash to recover the space.
9. Replace the drive with a larger one. Check out OWC for drives, tutorials, and toolkits.
10. Use OmniDiskSweeper or GrandPerspective to search your drive for large files and where they are located.

If you delete a lot of files but see no change in free space, then you have a big issue to deal with. Please see the following: Where did all that free space go on my APFS disk? and How to check a Mac’s free hard drive space and How to free up storage space on your Mac - Apple Support.

khabir.taylor wrote:

I am trying to free up disk space to install Catalina. I have deleted files using the storage manager and have also moved files to the trash and emptied the trash. However, my available disk space does not increase, even after deleting gigabytes of files. The amount of storage used for Documents goes down, but the total space used does not decrease.

The GUI is notoriously wrong or unrepresented in real time.

Highlight your Macintosh HD in the Finder or Desktop— Command i opens the info pane here you can see available/used storage

How to free up storage space on your Mac - Apple Support

https://support.apple.com/en-us/HT206996

User tip: "Other and What Can I Do About It ?"

https://discussions.apple.com/docs/DOC-5142

Try something likeOmniDiskSweeper for a GUI to get a good look at itemized file size and location:

OmniDiskSweeper http://www.omnigroup.com/more

Others for example—

Disk Inventory X: http://www.derlien.com/ (takes forever to load up.)

Grand Perspective: http://grandperspectiv.sourceforge.net/

Or alternatively from the Terminal.app, more detail copy and paste the command line:

File size, and finding missing GB— list the items in the home folder with the sizes, including invisible items.

sudo du -h -d 1 ~/

File size, and finding missing GB —will list the items in root with the sizes, including invisible items.

sudo du -h -d 1 /

Get Correct Storage Information

Do not use the information from the Storage section of the About This Mac dialog. Ignore the Storage information as it is typically wrong. To find out the correct information for any disk: Select a Desktop disk icon. Press Command-I to open the Get Info window and look at the topmost panel displayed. You will find the disk information displayed for Capacity, Available, and Used. If you have more than one disk/partition then repeat for each one on your Desktop.

The categories found in the Storage section of About This Mac is simply an arbitrary way of displaying files on your drive. There are no such categories actually on the drive.

You should not let your low free space continue or you will corrupt the drive. I think you should get an external drive on which you can create a backup. Then I would do a clean system recovery:

Install El Capitan or Later from Scratch

If possible, back up your files.

1. Restart the computer. Immediately, at or before the chime, hold down the Command and R keys until the Apple logo and progress bar appear. Wait until the Utility Menu appears.
2. Select Disk Utility from the Utility Menu and click on the Continue button.
3. When Disk Utility loads select the target drive (out-dented entry w/type and size info) from the Device list.
4. Click on the Erase button in Disk Utility's toolbar. A panel will drop down.
5. Set the partition scheme to GUID, if needed.
6. Set the Format type to APFS (SSDs only) or Mac OS Extended (Journaled.)
7. Click on the Apply button, then wait for the Done button to activate and click on it.
8. Quit Disk Utility and return to the Utility Menu.
9. Select Install OS X and click on the Continue button.

OmnidiskSweeper in Mojave:

I have 250GB on my SSD in my travel mac. And have a lot of user data on 2 external HDDs.

When I start Omnidisksweeper after disconnecting all externals:

and when I run it on maclex:

:

It shows everything on the disk, and shows where the bytes are. I showed the user library because there often is much space to save by deleting infos of old/unused apps.

Omni shows ALL on the disk.

I will add this article to Leroy's already excellent reply: Where did all that free space go on my APFS disk?

Where do you read "free space"?

If that is on AppleIcon->AboutThisMac->Storage: never look there again, it is always misrepresenting the truth.

As I said: don't look there. when you want to know it precisely:

SystemInformation in Utilities->Storage