How to Fix macOS 'Your Startup Disk Is Almost Full' Alerts and Reclaim Storage Space

Summary

This guide helps you troubleshoot and resolve: How to Fix macOS 'Your Startup Disk Is Almost Full' Alerts and Reclaim Storage Space. Follow the steps below to fix the issue.

Common Causes

When your Mac displays the alert “Your startup disk is almost full,” it means there is little free space left on the primary volume where macOS is installed. Running low on storage can slow down your computer, prevent software updates, and cause applications to crash. This guide helps small business and home office users across Brisbane and Australia identify large files, remove unnecessary system data, and reclaim storage space on their Mac.

Quick Fix Steps

1. Click the Apple menu in the top-left corner of your screen.
2. Select System Settings.
3. Click General in the sidebar, then select Storage.
4. Review the storage bar to see which categories are using the most space.
5. Click the i (information) button next to a category to view and delete large or unused files.
6. Empty the Trash to permanently remove deleted items.
7. Restart your Mac to clear temporary system files.

Detailed Instructions

Check Storage Usage

1. Open System Settings from the Apple menu.
2. Navigate to General > Storage.
3. Wait for macOS to calculate the storage breakdown.
4. Identify the largest categories, such as Applications, Documents, macOS, or System Data.

Remove Unused Applications

1. In the Storage window, click the i button next to Applications.
2. Sort the list by size to find the largest apps.
3. Select an application you no longer need.
4. Click Delete or Move to Trash.
5. Repeat for any other unused applications.

Clear Downloads and Documents

1. Open Finder.
2. Select Downloads from the sidebar.
3. Sort files by size to identify large installers, disk images, or old email attachments.
4. Move unwanted files to the Trash.
5. Repeat the process in your Documents folder.

Empty the Trash

1. Right-click the Trash icon in the Dock.
2. Select Empty Trash.
3. Confirm the action when prompted.

Clear System and User Caches

1. In Finder, click Go in the menu bar.
2. Hold down the Option key and select Library.
3. Open the Caches folder.
4. Move the contents of individual cache folders to the Trash, but do not delete the folders themselves.
5. Restart your Mac.

Review System Data

1. Return to System Settings > General > Storage.
2. Click the i button next to System Data.
3. Look for large Time Machine local snapshots, iOS backups, or old logs.
4. Remove any items you no longer need.

Troubleshooting

Storage Bar Does Not Update After Deleting Files

• Restart your Mac to allow macOS to recalculate available space.
• Check that you have emptied the Trash; deleted files still occupy space until the Trash is cleared.
• Wait several minutes for background indexing to finish.

Cannot Delete a File Because It Is in Use

• Close the application using the file, then try again.
• Restart your Mac and empty the Trash immediately after logging back in.
• Open Activity Monitor, locate the process using the file, and quit it before deleting.

Startup Disk Remains Full After Cleanup

• Move large photo, video, or archive files to an external drive or cloud storage.
• Check for large iOS device backups in ~/Library/Application Support/MobileSync/Backup.
• Review Storage settings for large email attachments or offline files.

If you continue to receive startup disk warnings after following these steps, Open a Ticket with 220 Internet Services for further assistance.

Still Having Issues?