9 incredibly easy ways to fix the "scratch disks are full" error on Mac

If you regularly work in programs like Adobe Premiere Pro, Final Cut Pro, and Adobe Photoshop, you’ve probably encountered errors relating to a "scratch disk." The most common error is Photoshop’s refusal to open, along with the message "Could not complete your request because the scratch disks are full."

If you’ve stumbled on this page because you’ve experienced this issue, you’re in luck: we’re going to show you how to resolve your scratch disk problem easily and, as a bonus, keep your computer clean and performing at its best.


What are scratch disks in Photoshop?

Before we highlight some solutions, it would be a good idea to have at least a general sense of what a scratch disk actually is. When you are using programs like Photoshop or Final Cut Pro, they require a working space called virtual memory or cache memory. This is where temporary project files are stored and accessed.

For this guide, we are focusing our laser sights on Photoshop. After all, it is the most common application. But rest assured that the info we cover will apply to most programs that rely on scratch drives.

Scratch disk is your hard drive space used by Photoshop as virtual memory when there is not enough RAM to complete a task. Photoshop allows you to assign several scratch disks: that way, it has more space at its disposal.

When working with large images and lots of layers, Photoshop is secretly chewing up your drive space by rapidly creating a mountain of project temp files.

It’s important to note that when you set up Photoshop, you will have the option to assign the scratch disks to the drive of your choice. We highly recommend not using your system drive unless you have no other alternatives.


Reasons behind “scratch disks are full” error

Temporary files are the most significant reason behind the “scratch disks are full” error. They usually mass up in your drive without leaving single evidence of their presence. If you have a habit of force-quitting Photoshop, you may have a lot of temporary files stored in your system. As Photoshop can’t fully close all projects after you quitted it so rapidly, it keeps such files on your machine. 

Here are some other reasons that may cause the mentioned message:

Lack of space

Little space left in the drive where the scratch disk is located

Full disk partitionThe partition of the disk being used by Photoshop is full
Limited RAM

Not enough memory allowed for Photoshop


What to do when your scratch disks are full?

Next, we’ll explain how to clear out the scratch disk and fix the Photoshop issue on a Mac. If you’ve faced a problem on the Windows computer, follow the instructions below.

How to clear scratch disks in Photoshop

Mac users receive a "scratch disk full" message when Photoshop (or any of the other programs) has used up all the space on the hard drive that has been assigned as a scratch disk. This used-up space is temporary and separate from your actual project file. 

The problem is that Photoshop doesn't always get rid of these temporary files when they aren't needed anymore, which is more like a permanent problem if the user can't find a solution.

So how to empty a scratch disk in Photoshop? Let's find out.


1. Clear your Photoshop cache

Photoshop has an in-built solution for deleting specific Photoshop caches. When these pesky caches aren’t removed automatically by the program, they can grow and take up a lot of space on your scratch disk.

To use this tool, simply enter Photoshop in Mac and with an image open:

  1. Click the Edit menu button.
  2. Hover your mouse over "purge" to reveal 4 different cache categories: Undo, Clipboard, Histories, All. Here's what they mean:
  • Photoshop records all commands you use while working on a project. Purging Undo sweeps away records about the most recently applied command. 
  • The Clipboard is a small part of memory that stores everything you copy. You can’t insert copied data after you purge the Clipboard.
  • Histories contain the previous versions of your project. Purging it will remove all history states saved previously, and you won’t be able to undo your latest actions. 
  • Clicking All will purge all your Photoshop caches. 
  • Video Cache stores changes you’ve previously made to the video project. You won't be able to restore changes, after you purge this category.

Select the specific item you want to delete or select "All" to delete all of your caches. If an item is greyed out, that means it has already been deleted.

You will be warned that the purge cannot be undone, so make sure you don’t need a previous version of one of your projects and then click OK.

    How your Scratch drive is filling up? An example from Sketch

    Along with Photoshop, Sketch is another app that keeps temporary versions of projects on your disk. And it eats up a whole lot: from 60 to 220 GB on average. Each time you press Command-S, some space is wasted away from your Scratch drive. Say your file weighs 23 MB. Then, 7 temporary editions would increase that size to 161 MB. This problem hasn’t been widely known until recently, but, luckily, there is an automatic solution. CleanMyMac’s System Junk module lists Documents’ Versions from Sketch and other similar apps. You can keep the final and the oldest version of a project and delete all revisions in-between. Voila, you’ve got free space again!


    2. Delete your temp files

    When it comes to wasting space on your scratch disk, Photoshop's own temp files are often the worst culprit. If Photoshop isn't going to get rid of them, I guess you're going to have to do the job yourself.

    To find them, you'll need to go to Finder and click the Go menu. Here, choose Go to Folder. Type /tmp in the field and press Enter. You could also search "Photoshop Temp" with a space between the two words right in your Finder search.

    You should see a list of files. If your work is saved and the program is closed, you can safely delete these files and watch as your scratch disk space is reclaimed.


    3. Clear your disk space

    If you don't have another drive or don't want to buy one, then it's time to do some spring cleaning. Look at the drive contents to see if you can delete anything you don't need. Is there storage space that can be cleared? Usually, there is, so go ahead and delete your old files and free up some space.

    Alternatively, you can simply transfer files to external drives, DVDs, or cloud storage solutions like Dropbox and iCloud.

    Your Mac already has the built-in tools to help you manage storage space. If you navigate to Apple Menu > About This Mac > Storage tab, you will see the storage graph.

    If you click on "Manage," you will see a list of recommendations. There are some truly helpful elements, like using Optimized Storage to customize what TV shows and movies you store on your Mac and Reduce Clutter option that allows you to view all your files, downloads, and unsupported apps. Explore the recommendations and tools and look for files you can remove to optimize your space.

    A good way to keep Photoshop cache from piling up is by running regular disk cleanups. But here is a problem: the cache sits so deep in system folders (and their subfolders) that deleting it manually becomes a pain. A company called MacPaw produced a tool just for this purpose, CleanMyMac X. You've heard of similar tools, but that one actually pioneered Mac cleanup.

    Here’s how you can schedule regular cleanings with CleanMyMac X:

    1. Launch CleanMyMac X tool.
    2. Click System Junk and press Scan.
    3. Click Review Details to deselect the data you want to keep.
    4. Hit Clean to clean up junk files.

    Just let it do its thing. That way, you’ll never forget to clear Photoshop cache and tons of other system junk on your system.

    You can download CleanMyMac X free version and see how it works.

    Tip

    If you're wondering how to fix a scratch disk error on Mac, here's our article you might find helpful — 11 quick ways to clean your disk space. Inside we have lots of practical advice for macOS users who want a clean drive that performs well.





    4. Change your scratch disk

    So, you've identified rapidly depleting free space on your Mac hard drive — now what? Well, it may be a good idea to change your scratch disk to another drive in your system (just not the system drive, as that is one drive you really don't want to slow down). If you don't have another drive, you could purchase one, with SSD being the best option for macOS scratch disk purposes.

    Follow these steps to change your scratch disk in Photoshop:

    1. Click on the Photoshop menu.
    2. Go to Preferences and then Scratch Disk.
    3. Tick the checkbox to select or remove a drive as the scratch disk.
    4. Click OK.
    5. Restart Photoshop.

    5. Consider buying a new SSD

    The scratch disk problem happens because of 2 simple reasons: lack of RAM and lack of free storage space. Both can be addressed if you buy a Thunderbolt SSD (solid-state drive) to use as your Scratch Disk. By today’s standards, 256 GBs should be enough.

    Tip

    It can be challenging to check and analyze all contents of your disk space. Luckily, some tools can provide a disk scan and can save up lots of space on your Mac. Apps notarized by Apple are best for this job. CleanMyMac X, the app I talked about earlier, has a Large & Old Files feature, which finds and removes massive files stored on your Mac.


    6.Follow the 15% rule

    Not strictly a rule, but rather a common practice states that you should keep at least 10-15% of your disk space free at all times. If your storage size is 256 GB, your lower limit is 25 GB. You’ll have enough room to render your Photoshop files, save multiple project copies, etc.

    Tip

    Loud fans noise is a sign your CPU is overloaded and approaching its carrying capacity. Try closing active apps you don't use to lighten the load for your Mac's CPU: press Command-Option-Esc and select unused program. Click Force Quit to quit the selected app. 


    7. Free up RAM in Terminal

    When Photoshop gets paralyzed due to lack of RAM, there is a command you can run in Terminal. 

    1. Open the Terminal app (find it in the Launchpad).
    2. Paste in: sudo purge
    3. Then, enter your password.

    At first, you may not see the difference, but you’ve just flushed your RAM, releasing all the files kept in virtual memory. There are a few more ways to free up RAM; check them out too.

    You can also download CleanMyMac X (get a free edition here) and use its Free UP RAM command. 

    1. Install the app and click on Maintenance.
    2. Select Free Up RAM and click Run.

    You can apply this trick anytime to unfreeze an app. Also, check out the other tools in the Maintenance section. They will help you take some load off your Mac’s memory.


    8. Reset Photoshop preferences

    One way to fix the “Scratch disks are full” error is to reset Photoshop preferences. Here’s how to do that:

    1. Open Photoshop.
    2. Click the Photoshop menu in the top right.
    3. Here, choose Preferences and then General.
    4. In the window that appears, click “Reset Preferences On Quit.”
    5. Click “OK” to confirm.

    Now, you need to quit Photoshop to complete the reset. Close the app or click Photoshop menu > Quit. Restart the application and see if the problem persists.


    9. Disable auto-recovery

    The auto-recovery is a very useful feature that helps you make sure no progress will be lost. But, if you’re experiencing the “scratch disks are full” error on a Mac, disabling auto-recovery might save you some gigabytes of space. So, here’s how to turn off the auto-recovery in Photoshop:

    1. Go to Photoshop menu > Preferences.
    2. Select File Handling from the left-side menu.
    3. Uncheck the “Automatically Save Recovery Information” box.

    Now all your progress won’t be automatically saved.


    How to clear the scratch disk on Windows

    If you are experiencing a “scratch disks are full” error on your Windows computer, freeing up space in the drive that accommodates the scratch disk may fix the problem. To do that, you need first to find out which drive Photoshop uses as a scratch disk. 

    1. Open Photoshop and go to Edit > Preferences. 
    2. Choose Scratch Disks. 
    3. Check which drive is used as a scratch disk. 

    The scratch disk should have at least 40GB of free space. If you see that it’s running out of space, access the drive and remove or transfer the largest files. 

    Another thing you may do to fix the error is clear out Photoshop temporary files. Just make sure you save your work first and close all Adobe apps. Then, go to the temp data folder
    C:\Users\Your Username\AppData\Local\Temp. Look for the files that have “Photoshop Temp” in their names, highlight and remove them.


    The 'Scratch Disk Is Full' error is fixed!

    If you followed this guide, there is absolutely no reason why you should ever have to deal with the annoying "scratch disk full" error again. Next time you want to create something amazing in Photoshop, you should experience something new - a Photoshop that runs so smoothly it practically purrs.

    Whether you solve the problem yourself or let a great piece of software like CleanMyMac X do it for you, just make sure you clean up your scratch disk. Your Mac will thank you for it*.

    *Not literally. That would be weird.


    Frequently asked questions

    Why the “scratch disks are full” error may appear?

    The number one reason for the “scratch disks are full” message is the lack of space in the drive where scratch disks are located. You can also run out of space in the partition of the disk allocated for Photoshop, which may also cause the above-mentioned error.

    What are Photoshop temporary files?

    Temporary files will appear if you don’t close Photoshop fully or open the Smart Object and don’t close them with the Smart Object layer. Photoshop temp files have a ".tmp" extension, so it’s easy to find them on your Mac.

    How to fix the “scratch disks are full” Photoshop issue?

    One of the solutions is to change the scratch disk allocation. You may also need to clear the Photoshop cache and remove temporary files.

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