Photoshop scratch disk full: check storage before resetting preferences

Start with the drive Photoshop is actually using

If an unsaved document is open, try to save your work before restarting. Do not delete unfamiliar temporary files while Photoshop is running, and do not erase project files simply because a cleanup utility labels them large.

If Photoshop still opens

1. Open Edit > Preferences > Scratch Disks on Windows or Photoshop > Settings > Scratch Disks on macOS.
2. Note which drives are selected. Check available space on those drives in your operating system.
3. Move expendable downloads or already-backed-up material elsewhere. Confirm that moved files open before removing the original copies.
4. If another suitable drive is available, select it in Scratch Disk preferences and arrange the priority. Save your documents, restart Photoshop, and repeat the operation that failed.

Adobe documents scratch-drive selection and priority here. Its current scratch-disk troubleshooting guide recommends freeing at least 100 GB on the primary scratch drive. This is a troubleshooting target, not a promise that every document will fit.

If Photoshop cannot launch

Adobe documents a startup shortcut for choosing a different scratch disk: hold Ctrl + Alt on Windows or Command + Option on macOS while launching Photoshop. Use this only when you have another appropriate drive available; it cannot create free storage.

This shortcut is different from the three-key shortcut that deletes Photoshop preferences. Avoid following a preference-reset instruction when your immediate goal is simply to change the scratch drive. See Adobe’s performance guide for the startup option.

If one document keeps triggering the error

After saving your work, close unrelated documents and compare a small existing image with the troublesome file. Record the failing operation and the document's pixel dimensions and layer count. That comparison is more useful than repeatedly clearing space without knowing which operation consumes it.

Adobe notes that history states consume working storage. Reducing their number can help, but gives you a shorter editing history. Record the original setting before changing it. Purging history also removes undo options; treat it as a deliberate tradeoff, not a routine first step.

When to stop and ask for help

If ample space is available on the selected drive and even small files fail, use Adobe Photoshop Help. Include the exact error, Photoshop and OS versions, selected scratch drives, available space, and the operation that fails. This guide is based on documentation; we have not reproduced the error on a test machine.