How to Fix Photoshop Scratch Disk Full Errors

Troubleshooting steps and fast fixes to free up space for photo editing

The Photoshop scratch disk is your hard drive. Photoshop uses your hard drive as temporary "swap" space, or virtual memory when your system does not have enough RAM to perform an operation. If you only have one hard drive or partition in your computer, then the scratch disk will be the drive where your operating system is installed (the C: drive on a Windows system).

The tips and techniques we outline are based on Adobe Photoshop CC.

Setting Up Scratch Disks

Screenshot of Photoshop CC menu, Preferences, Scratch Disks...

You can change the scratch disk location and establish addition scratch disks from Photoshop Preferences (On Windows: Edit > Preferences > Scratch Disks, On Macintosh: Photoshop CC Menu > Preferences > Scratch Disks). Many power users like to create a dedicated hard drive partition for the Photoshop scratch disk. Although Photoshop will function with a single scratch disk on the system partition, you can improve performance by setting the scratch disk to be the fastest drive in your system. Other useful guidelines for setting scratch disks are to avoid using the same drive where your operating system is installed, avoid using a drive where the files you edit are stored, and don't use network or removable drives for a scratch disk.

If your computer has a fast solid state disk drive (SSD), you should use the SSD as your scratch disk, even if it is your system drive.

Delete Photoshop Temp Files

If Photoshop is shut down improperly or crashes in the middle of an editing session, this improper shutdown may leave fairly large temporary files behind on your scratch disk. Photoshop's temp files are typically named ~PST####.tmp on Windows and Temp#### on Macintosh, where #### is a series of numbers. These are safe to delete.

Clear Disk Space

If you're getting an error message that the scratch disk is full, it usually means you need to clear some space on whatever drive is defined as the scratch disk in Photoshop Preferences, or add additional drives for Photoshop to use as scratch space.

Defragment Your Hard Disk

It is also possible to get the "scratch disk is full" error, even if the scratch disk drive has free space. This is because Photoshop requires contiguous, unfragmented free space on the scratch disk drive. If you are getting the "scratch disk is full" error message and your scratch disk drive does show a good amount of free space, you may need to run a disk defragmentation utility.

Scratch Disk Errors When Cropping

Screenshot of Clear crop tool button in Photoshop

If you are getting a "scratch disk full" error when attempting to crop an image, it's likely that you inadvertently have size and resolution values entered in the options bar for the crop tool, or you entered values in the wrong units. For instance, entering dimensions of 1200 x 1600 when your units are set to inches instead of pixels is going to create a huge file that could trigger the scratch disk full message. The solution is to press Clear in the options bar after selecting the crop tool but before dragging a crop selection. (See: Fixing Problems with Photoshop's Crop Tool)

Switch Scratch Disks

Screenshot of Scratch Disks panel in Photoshop focusing on the hard drive selected

If you open Photoshop Preferences you can select the Scratch Disks category to open the Scratch Disk preference pane. Here you will see a list of all of the drives currently connected to your computer. Select one of the drives to switch from the current Scratch Disk. You can also press Command-Option (Mac) or Ctrl-Alt (PC) when launching Photoshop to change the Scratch Disk.

More on Scratch Disk

For more on how Photoshop uses RAM and scratch disk space, (see Memory allocation and usage (Photoshop CC) from Adobe), or look up "assigning scratch disks" in the online help for your version of Photoshop.