6 Ways to Clear Scratch Disk in Photoshop on Mac


Peter Aaron

5 min read

If you frequently use Photoshop on your Mac, you may encounter the Photoshop scratch disk full error when saving pictures or launching Photoshop. So what does this error message mean, and how can you fix it on Mac?

Don't worry. In the following content, we will introduce to you what a scratch disk is, why there is a scratch disk full error in Photoshop, and most importantly, how to fix it.

Photoshop Scratch Disk Full on Mac? Here's How 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 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.

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, you can check it by clicking the Apple Menu > About This Mac > Storage.

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

Scratch Disk Full Error

How to Clear Photoshop Scratch Disk Space 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 solve it. Next, we will introduce you 6 ways to clear Photoshop's scratch disk. Let's find them out.

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. Purge Photoshop Cache
  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

According to Adobe articles, 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 normally.

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. You can click How to Free up Mac Storage Space for more tips.

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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. Clear Photoshop Temporary Files

4. Change Photoshop Scratch Disk

If you still cannot free up enough disk space for Photoshop, you can select another disk as your scratch disk. But if you don’t have another disk to choose from, you may need to add a new disk to your Mac, and SSD is your best choice.

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. Change Photoshop 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, 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. Change RAM for Photoshop

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. Disable Auto Recovery
  • 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. Limit History States


Now you know how to fix the scratch disk full error in Photoshop on Mac. In fact, there are many more ways you can try, such as increasing RAM, resetting Photoshop preferences, defragmenting your hard drive, and more.

Hopefully, you can solve the Photoshop full scratch disk problem through one or more methods above. If you find this article helpful, please don't forget to share it with your friends.


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