Photoshop Error — Scratch Disks Are Full

What Does This Error Mean?

Photoshop uses scratch disks as temporary storage — like a work table — when it runs out of RAM. When that storage space fills up, Photoshop cannot continue and shows this error. The fix is either freeing up disk space or pointing Photoshop to a different, less-full drive.

Affected Models

Adobe Photoshop CC
Adobe Photoshop CS6
Adobe Photoshop 2022
Adobe Photoshop 2023
Adobe Photoshop 2024

Common Causes

The scratch disk drive (usually your C: drive) is almost full
Photoshop's scratch disk cache has grown very large over time
Photoshop is only assigned one small drive as its scratch disk
You are working with very large files or many open documents
Temporary files from previous Photoshop sessions were not cleaned up

How to Fix It

In Photoshop, go to Edit > Purge > All. This clears Photoshop's internal cache of undo history and clipboard data.

Warning: purging clears your undo history. Save your work first.
If Photoshop will not open at all, hold Ctrl+Alt (Windows) or Cmd+Option (Mac) while launching Photoshop to open the scratch disk selector.

This lets you change the scratch disk before Photoshop fully loads.
Go to Edit > Preferences > Scratch Disks. Add a second drive with more free space, or switch to a drive that has more room.

If you have an external hard drive or a second internal drive, it can make an excellent scratch disk.
Free up space on your scratch disk drive. Delete unused files, empty the Recycle Bin, and clear your browser cache. Aim for at least 20 GB free.

Photoshop can need many gigabytes of scratch space when working on large files.
In Preferences > Performance, reduce the History States count from the default 50 to around 20. This reduces how much scratch space Photoshop needs.

Fewer history states means less scratch disk usage, but also fewer undos.

When to Call a Professional

This is a storage and settings issue you can solve yourself. If your system drive is critically full and you cannot free up space, a technician can help move files to an external drive or add more internal storage.

Frequently Asked Questions

What exactly is a scratch disk?

Think of RAM as your desk and your hard drive as a filing cabinet. When your desk (RAM) is full, Photoshop starts piling work onto the floor (the scratch disk). When the floor is full too, Photoshop stops and shows this error.

Can I use an external USB drive as a scratch disk?

Yes, but only if it is a fast drive — ideally a USB 3.0 solid-state drive. A slow USB thumb drive will make Photoshop run very sluggishly. A fast external SSD works well.

How much free space does Photoshop need?

Adobe recommends having at least 20 GB free on your scratch disk drive. For very large files (100 MB+) or complex compositing work, you may need 50 GB or more. Photoshop can use up to 10 times the file size as scratch space.