Therefore, you need to take measures like cleaning junk files on Mac to avoid seeing the startup disk full error again. Worse, with a large amount of storage was occupied on the startup disk, Mac may fail to upgrade macOS, run slowly, or behave abnormally. This dread warning will appear on your Mac when the space of Mac's startup disk is going to be full. What does 'Your disk is almost full' mean This post aims to help you free up space on Macintosh HD in multiple ways and reclaim more available space to use. Over time, the stored files on your Mac's startup disk pile up, and the available storage space has become less and less. For most Mac users, there is only one disk physically built into your Mac, so the unique disk is the startup disk. Then expand them when you need to use them again.ĭid you empty the Trash? When you move a file to the Trash, its storage space doesn't become available until you empty the Trash.The Startup disk is the hard drive where the computer's operating system and applications are installed. If you don't want to delete certain files, you might be able to save space by compressing them. Check the Users folder on Macintosh HD for any shared files that you no longer need to share.If your Mac is set up for multiple users, delete users that no longer need access to your Mac. Or ask them to follow the steps in this article after logging in to their user account. Also check the Users folder on Macintosh HD for any undeleted data belonging to deleted users.If you use your Mac to back up your iPhone or iPad, you can delete old backups.Also choose Mailbox > Erase Deleted Items. If you use the Mail app for your email, choose Mailbox > Erase Junk Mail from the menu bar in Mail.Delete files in your Downloads folder. Open this folder from the Dock, or by choosing Go > Downloads from the menu bar in the Finder.Delete music, movies, podcasts, or other media, especially if it's media that you can stream or download again as needed.You can also delete files that you no longer need. If you have another storage device, such as an external drive connected to your Mac, you can move files to that device. Media files such as photos and videos can use a lot of storage space, so you can take steps such as these: