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

If you've stumbled on this page because you've experienced the full scratch disk 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. Keep on reading to find out the following:

How to clear scratch disk on Mac?

First, we'll explain how to clear Photoshop scratch disk and fix the scratch disk full issue on a Mac.

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 your disk space.

To use this tool, simply launch Photoshop on your Mac and follow these steps with an image open:

  1. Click the Edit menu button from the menu bar.
  2. Hover your mouse over "Purge" to reveal 4 different cache categories: Undo, Clipboard, Histories, and 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 cache files. 
  • Video Cache stores changes you've previously made to the video project. You won't be able to restore changes after you purge video cache.

To clear Photoshop cache and possibly fix the scratch disks problem, choose the specific item you want to delete or select "All" to delete all of your cache files. 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 these temporary files eat up a whole lot: from 60 to 220 GB on average. Each time you press Command-S, some disk space is wasted away from your scratch disk. Say, your file weighs 23 MB. Then, 7 temporary editions would increase that size to 161 MB. Some of them are duplicate files. This problem hasn't been widely known until recently, but luckily, there is an automatic solution. The CleanMyMac's Cleanup feature identifies document 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 disk space again and may avoid the scratch disk full error.

    CleanMyMac - Document versions

    2. Delete your temp files

    When it comes to your scratch disk space waste, Photoshop's own temp files are often the worst culprit. So, why store temporary files? Deleting these files may help you forget about the scratch disk full error message. Note that you may need to do it if you can't delete Photoshop's cache files, which is a rare occasion. 

    Before deleting temporary files, make sure to save your progress and close Photoshop. Now, you're ready to move on. 

    To find temporary Photoshop files:

    1. Go to Finder and click Go from the menu bar. 
    2. Here, choose Go to Folder. 
    3. Type /tmp in the field and press Return. 

    This will open a new folder window that contains Photoshop files and folders. Now, as you see the list, carefully go through all of the folders and delete files that eat up the space of Photoshop scratch disks. Make sure you select only temporary files — those with the .tmp extension.

    Alternatively, you could also search "Photoshop Temp" with a space between the two words right in your Finder search. Following the same logic as described above, you can safely delete files and watch as your scratch disk space is reclaimed. Get rid of as many files as you can.

    Now, launch Photoshop once again. Hopefully, the scratch disk full errors are gone; if not, keep on reading to learn more tips. 

    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 to reclaim some disk space. 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 > More Info > Storage Settings, you will see the storage graph.

    System Preferences - Storage

    Besides, you will see a list of recommendations. There are some truly helpful elements, such as using Optimize Storage to customize what TV shows and movies you store on your Mac and the option that allows you to view all your files, downloads, and unsupported apps. Explore the recommendations and tools to look for files you can remove to optimize your space and solve the problems with Photoshop scratch disks.

    A good way to keep Photoshop cache from piling up is by running regular disk cleanups. It will help get rid of junk files that may be causing the scratch disk error. 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. You've heard of similar tools, but that one actually pioneered Mac cleanup.

    Here's how you can schedule regular cleanings with CleanMyMac:

    1. Open CleanMyMac.
    2. Go to Cleanup and click Scan.
    3. Hit Clean to clean up junk files, or Review All Junk to select the items you’d like to remove.

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

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

    Tip

    If you're wondering how to fix the Photoshop scratch disk error on Mac, here's our article you might find helpful — quick ways to clean your disk space. Inside, we have lots of practical tips 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 as one of the factors behind the Photoshop scratch disk problem — now what? Well, it may be a good idea to change your scratch disk to another drive in your system. Just make sure it's 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 Photoshop scratch disk purposes.

    Follow these steps to change your scratch disk using Photoshop preferences:

    1. Open Photoshop.
    2. Go to Photoshop > Preferences from the menu bar. 
    3. Select Scratch Disks and tick the checkbox to select or remove a drive as the scratch disk.
    4. Click OK.
    5. Reopen Photoshop.

    5. Consider buying a new SSD

    As mentioned, 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 Photoshop 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 save up lots of space on your Mac. Apps notarized by Apple are best for this job. CleanMyMac, the app we talked about earlier, has the My Clutter feature, which finds and removes massive files and other clutter stored on your Mac. With its help, you can delete files that take up a lot of space but are actually no longer needed.

    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 fan 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 (get a free edition here) and use its Menu to manage your memory usage.

    Memory

        • Install the app and click the CleanMyMac Menu icon in your menu bar.
        • Click Free Up on the Memory panel.

        You can also open the Memory panel to see which apps are using too much memory and quit them to improve your Mac's performance.

        8. Reset Photoshop preferences

        Resetting Photoshop's preferences is one way to fix the "Scratch disks are full" error. Here's how to do that:

        1. Open Photoshop.
        2. Go to Photoshop preferences: from the menu bar, choose Preferences > General.
        3. In the window that appears, click "Reset Preferences On Quit."
        4. Click "OK" to confirm.

        Now, you need to quit Photoshop to complete the reset. Quit the app or click Photoshop menu > Quit. Launch Photoshop once again and see if the scratch disk error message persists.

        9. Disable auto-recovery

        It's great to automatically save recovery information — it 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.
        3. Deselect the "Automatically Save Recovery Information" box.

        Now, all your progress won't be automatically saved, so don't forget to use Command-S occasionally. 

        What are scratch disks in Photoshop?

        Scratch disk in Photoshop is your hard drive space used by the app 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 for storing temporary files 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 and cache files.

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

        Why scratch disks are full?

        Photoshop's 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 quit it so rapidly, it keeps such files on your computer.

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

        Lack of space

        Little space left in the drive where Photoshop's 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

        How to empty scratch disk without opening Photoshop?

        You may be wondering how to fix scratch disk full in Photoshop without even opening it. Most commonly, it may be the case if you can't open Photoshop and use any of the solutions based on Photoshop Preferences. Luckily, there are a few workarounds you can try:

        • Free up RAM using Terminal as described in step 7.
        • Use Activity Monitor to quit memory-intensive apps. Open Activity Monitor, click Memory, and see what apps and processes use the most memory. You may also want to type 'Photoshop' in the search bar and quit anything related to it. Make sure to research what the names of the processes stand for to avoid quitting something vital for macOS.

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        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 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

        What are scratch disks in Photoshop?

        Scratch disks are the space on the hard drive or SSD that is used for storing temporary files in Photoshop. These files are, for example, unsaved parts of the documents you worked on. 

        Is it possible to empty scratch disks in Photoshop? 

        The short answer is yes. It is done from the Edit menu (found in the menu bar with Photoshop open) and clearing out different types of caches by clicking Purge. This action is irreversible and temporary, though. 

        Is it safe to empty scratch disks in Photoshop? 

        It is generally safe. The only concern to consider is that temporary files will be lost, so make sure that all important changes have been saved.