How to Clear Scratch Disk and Photoshop Cache on Mac

Photoshop is a really powerful tool but like many other powerful applications, it also has a lot of intricacies and can sometimes throw a curve ball at users who are not familiar with all its quirks.

One such unexpected situation is finding yourself unable to keep working on an increasingly complex Photoshop project or even being unable to boot the application. Those issues are often caused by filling up the application's scratch disk.

The so-called 'scratch disk' of Photoshop is really the disk drive cache that the software creates. In addition to loading its needed information in RAM, Photoshop will also extend this volume of information on your hard drive, in case your project is too big to store entirely in system memory.

When you use the application normally, those excess files stored on your disk drives are deleted upon closing the program. However, crashes and forced exits of the software will not wipe the disk cache, and this can lead to your scratch disk getting gradually too full.

In order to clear your Photoshop cache, you can do the following:

  1. With Photoshop open and a problematic project loaded in, click on Edit > Purge > All.
  2. Click OK to confirm the next prompt.
  3. Check to see if the 'scratch disk full' error persists.

In order to delete any temporary files created by Photoshop, do the following:

  1. Use Finder's 'Go' button, then type '/tmp' in the dialog box and click 'Go'.
  2. In the new view that opens, find a folder named 'PhotoshopTemp'. It may also have a numerical string attached to its end.
  3. Drag and drop the contents of this folder to your Trash.

You can also consider manually freeing up additional disk space on whatever system disk drive Photoshop uses for its temporary 'scratch disk' storage.

If you cannot afford to delete any additional large files from that drive, consider getting additional storage or even an external drive that you can assign for dedicated 'scratch disk' storage for your Photoshop large projects.

September 23, 2021