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

Peter Aaron
Last updated: Mar 22, 2023

Summary: In this guide, we will tell you why your Photoshop prompts the error that the scratch disk is full and show you how to fix the problem on Mac in 6 ways.

As you are reading this, you probably have encountered the scratch disk full error in Photoshop on your Mac. A full scratch disk means you can't perform edits, save images, or even start Photoshop.

Wondering why this problem occurs and how to fix it on Mac? Keep reading this blog and you will find all the answers you are looking for.

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

What Is the Scratch Disk in Photoshop?

Before we offer you the solutions to the full scratch disk problem in Photoshop, let's find out what a scratch disk is.

According to Adobe, a scratch disk is a hard drive or SSD that is used for temporary storage while Photoshop is running. Photoshop uses 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 the 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 main reason why Photoshop’s scratch disk is full. As you know, Photoshop is a large design program. When you use it to create and edit images, it generates a large number of temporary files that can make Photoshop run faster. But over time, these files pile up and take up a lot of the space of the scratch disk.

In addition, when the hard drive used as the scratch disk runs out of storage space, you may also get the prompt window that says the scratch disk is full. To find out if you have any 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 limited RAM for Photoshop. In this case, you may need to add more memory.

How to Clear Scratch Disk in Photoshop on Mac

After understanding what a scratch disk is and why the scratch disk full error occurs in Photoshop, we come to the most important part of how to clear scatch disk in Photoshop.

1. Clear Photoshop Cache

Photoshop has a built-in cleaning function that allows you to clean up the history and caches in Photoshop. But 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.

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

    How to Purge Photoshop Cache on Mac
  3. You will be prompted to a new window that warns your deletion cannot be restored. Click the OK button if you are sure to go.

2. Free up Disk Space

Adobe says that you should reserve at least 20GB of free space on your macOS hard drive while working with Photoshop. Depending on the type of file you are working on, you may also need to set aside additional storage space to ensure that Photoshop runs properly.

There are various ways to free up your Mac disk space, such as deleting useless files, removing duplicate files, uninstalling unwanted apps, moving files you don't use currently to another disk, etc.

Here we would like to introduce you a handy tool - BuhoCleaner, one of the best cleaners for Mac. Not only can it help you clear junk files from the system, users, and applications, but it can also speed up your process of finding and deleting large files and duplicate files. Click the button below to have a try now.

Quickly Clean Up Mac with BuhoCleaner

3. Delete Photoshop Temporary Files

Photoshop creates a lot of temporary files as you use it. You can go to Finder to find and delete these temporary files manually. Most of the time, the temporary files start with pst, followed by numbers, and end with a .tmp extension.

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 appeared list, find the temporary files you want to remove and drag them to the Trash.
    Delete Photoshop Temporary Files
This process may take you some time. You'd better make sure the files you want to get rid of are no longer useful to you before deleting them.

4. Change Photoshop Scratch Disk

Still haven't freed up enough disk space for Photoshop? Choose another disk as a scratch disk. If you don't have another disk to choose from, you'll need to add a new disk on your Mac first. SSD is your best bet.

Here's How to Change 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 press and hold the Command + Option keys while launching Photoshop to quickly change your scratch disk.

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 that you do not exceed 85% at most. Otherwise, it may cause poor performance of other applications due to insufficient memory.

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

6. Optimize Photoshop Space

You can also optimize the space Photoshop uses by disabling the auto-recovery saving and limiting the 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, and it presets the number to 50. To reduce the number, click the Photoshop Menu > Preferences > Performance and change the number to any number you like.
How to Limit History States in Photoshop on Mac


You have just learned how to fix the scracth disk full error in Photoshop on Mac. We hope that you have succesfully resolved it by using the above methods. If not, there are many more ways you can try, such as increasing RAM, resetting Photoshop preferences, defragmenting your hard drive, and more.

By the way, BuhoCleaner is a worthwhile cleaner that can be your perfect tool for cleaning and optimizing your Mac. Go ahead and try it yourself.