Photoshop Scratch Disk Full on Mac? 6 Ways to Clear It

Kelly Wu
Last updated: Sep 12, 2023
Summary: In this guide, we will explain why your Photoshop might display the error that the scratch disk is full and provide you with six methods to resolve the issue on your Mac.

If you're currently reading this, chances are you've encountered the "scratch disk full" error in Photoshop on your Mac. A full scratch disk can prevent you from making edits, saving images, or even starting Photoshop.

Are you wondering why this problem occurs and how to fix it on your Mac? Continue reading this blog, and you'll discover all the answers you're seeking.

Photoshop Scratch Disk Full on Mac? 6 Ways to Clear It

What Is the Scratch Disk in Photoshop?

Before we provide solutions to the full scratch disk problem in Photoshop, let's understand what a scratch disk is.

According to Adobe, a scratch disk is a hard drive or SSD used for temporary storage while Photoshop is running. Photoshop utilizes this space to store portions of your documents and their history panel states that don't fit in your Mac's memory or RAM. By default, Photoshop uses the hard drive (Macintosh HD) where macOS is installed as the primary scratch disk.

Scratch Disk Full Error in Photoshop

Reasons Behind the Full Scratch Disk Error in Photoshop

Temporary files are the primary reason for Photoshop's scratch disk becoming full. As you know, Photoshop is a large design program. When you use it to create and edit images, it generates a significant number of temporary files that can enhance Photoshop's performance. However, over time, these files accumulate and consume a substantial amount of space on the scratch disk.

Additionally, if the hard drive used as the scratch disk runs out of storage space, you may receive a prompt stating that the scratch disk is full. To check for available storage space, click the Apple Menu > System Settings > General > Storage.

Check Free Storage Space on Mac

Another reason behind the scratch disk full error is insufficient RAM for Photoshop. In this case, you may need to add more memory.

How to Clear the Scratch Disk in Photoshop on Mac

Now that we understand what a scratch disk is and why the scratch disk full error occurs in Photoshop, let's focus on the most crucial part: how to clear the scratch disk in Photoshop.

1. Clear Photoshop Cache

Photoshop features a built-in cleaning function that allows you to remove history and caches. Please note that this cleanup is irreversible, and all deleted history and caches cannot be restored.

Here's how to clear the caches in Photoshop:

1.Open Photoshop on your Mac.

  1. Click the Edit button in the menu bar, hover your mouse over Purge, and select the item you want to clear or choose All to remove all caches in Photoshop.

    How to Purge Photoshop Cache on Mac
  2. A new window will appear, warning you that your deletion cannot be undone. Click the OK button if you are sure.

2. Free Up Disk Space

Adobe recommends reserving at least 20GB of free space on your macOS hard drive when working with Photoshop. Depending on the type of files you are working with, you may also need to allocate additional storage space to ensure Photoshop runs smoothly.

Various methods can help you free up your Mac disk space, including deleting unnecessary files, removing duplicates, uninstalling unwanted apps, and moving files you don't currently use to another disk.

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3. Delete Photoshop Temporary Files

As you use Photoshop, it generates numerous temporary files. You can manually find and delete these temporary files using Finder. Typically, temporary files start with "pst", followed by a number and end with a ".tmp" extension.

Here are the steps:

Here are the how-to steps:

  1. Click the Finder icon on the Dock.
  2. Type "Photoshop Temp" in the search box in the upper right corner of the Finder window.
  3. In the list that appears, locate the temporary files you want to remove and drag them to the Trash.
    Delete Photoshop Temporary Files
This process may take some time. Ensure that the files you want to delete are no longer useful to you before proceeding.

4. Change Photoshop Scratch Disk

If you haven't freed up enough disk space for Photoshop, consider selecting another disk as a scratch disk. If you don't have an alternative disk, you may need to add a new one to your Mac, and an SSD is an excellent choice.

Here's how to change the scratch disk in Photoshop:

  1. Click the Photoshop Menu > Preferences > Scratch Disks.
  2. Check the box to select or delete the disk as the scratch disk, and then click the OK button.
  3. Relaunch your Photoshop.
How to Change Photoshop Scratch Disk on Mac
You can also quickly change your scratch disk by pressing and holding the Command + Option keys while launching Photoshop.

5. Change RAM for Photoshop

By default, Photoshop uses 70% of the memory space. You can adjust this value as needed. However, we strongly recommend not exceeding 85% to prevent poor performance in other applications due to insufficient memory.

  1. Click the Photoshop Menu, then select Preferences > Performance.
  2. Use the memory usage slider to adjust the amount of memory allocated to Photoshop.
  3. Click OK and then restart Photoshop.
How to Change RAM for Photoshop on Mac

6. Optimize Photoshop Space

You can optimize the space Photoshop uses by disabling auto-recovery saving and limiting history states.

  • To stop the auto-recovery saving, click the Photoshop Menu > Preferences > File Handling and untick the box next to Automatically Save Recovery Information Every.
How to Disable Auto Recovery of Photoshop
  • Photoshop can save up to 1000 history states, with the default set to 50. To reduce this number, go to the Photoshop Menu > Preferences > Performance and adjust the number to your preference.
How to Limit History States in Photoshop on Mac


You have now learned how to resolve the scratch disk full error in Photoshop on your Mac. We hope you have successfully addressed this issue using the methods described above. If not, there are additional approaches you can explore, such as increasing your RAM, resetting Photoshop preferences, defragmenting your hard drive, and more.

Additionally, BuhoCleaner is a valuable tool for cleaning and optimizing your Mac. Feel free to give it a try.

Living in Chengdu, Kelly is an Apple technician focused on Mac, iPhone, and iOS repairs. Meanwhile, he's also a columnist at Dr.Buho, with a simple mission to help fix Apple things that are with software or hardware glitches.