How to Clear Scratch Disk Space and Fix "Scratch Disk Full" Errors

If you've ever seen the message "Could not complete your request because the scratch disk is full" — usually mid-session in Photoshop or another creative app — you already know how disruptive it can be. Clearing your scratch disk isn't complicated, but doing it effectively depends on understanding what's actually happening under the hood.

What Is a Scratch Disk?

A scratch disk is temporary storage space that applications use when they run out of RAM. Instead of crashing or refusing to work, programs like Adobe Photoshop, Premiere Pro, and After Effects offload temporary data — undo states, cached layers, render previews — onto your hard drive or SSD.

Think of it as overflow parking. RAM is the main lot; the scratch disk is where the extra cars go when it fills up.

By default, most applications assign your primary system drive (typically your C: drive on Windows or Macintosh HD on macOS) as the scratch disk. That's fine until your drive is nearly full — at which point the app has nowhere to write its temporary files.

Why Scratch Disks Fill Up

Several things contribute to scratch disk saturation:

• Large working files with many layers or high resolution canvases consume scratch space aggressively
• Accumulated cache files from previous sessions that weren't properly cleared
• Low free storage on the assigned drive — even if the scratch disk itself isn't the problem, the drive being near capacity triggers the error
• Multiple applications sharing the same scratch disk simultaneously
• Crash leftovers — when an app exits unexpectedly, temporary scratch files often don't get cleaned up automatically

How to Clear Your Scratch Disk 🗂️

1. Purge Cache from Within the Application

In Adobe Photoshop, go to: Edit → Purge → All

This clears the clipboard, undo history, and video cache stored in memory and on the scratch disk. Note that this action cannot be undone — your undo history will be wiped.

In Premiere Pro, navigate to: Edit → Preferences → Media Cache → Delete

Each application handles this differently, but most creative tools have some version of a cache or purge menu.

2. Manually Delete Temporary Files

On Windows:

• Press Win + R, type %temp%, and press Enter
• Select all files in the folder and delete them
• Skip any files that are currently in use

On macOS:

• Open Finder, press Cmd + Shift + G, and type ~/Library/Caches
• Look for folders associated with the application causing issues and trash their contents
• Empty the Trash afterward

These temp folders can accumulate gigabytes of orphaned data over time, especially after application crashes.

3. Change the Scratch Disk Location

If your primary drive is consistently low on space, reassigning the scratch disk to a different drive is often the more sustainable fix.

In Photoshop: Edit → Preferences → Scratch Disks (Windows) or Photoshop → Preferences → Scratch Disks (macOS)

You can designate a secondary internal drive, an external SSD, or a dedicated partition as your scratch disk. The key factors here are drive speed and available capacity.

4. Free Up Space on the Assigned Drive

If changing the scratch disk isn't an option, the straightforward path is reclaiming storage on the existing drive:

• Uninstall unused applications
• Move large media files (videos, RAW photos, project archives) to external storage or cloud backup
• Use built-in tools like Windows Storage Sense or macOS Storage Management (About This Mac → Storage → Manage) to identify what's consuming space
• Empty your Trash/Recycle Bin — surprisingly often overlooked

5. Increase RAM to Reduce Scratch Disk Dependency

Scratch disk issues are ultimately a symptom of RAM pressure. The more RAM an application can use directly, the less it needs to write to disk.

In Photoshop, you can control how much RAM the app is allowed to use under: Preferences → Performance → Memory Usage

Increasing this allocation (if your system has spare RAM) reduces how quickly the app reaches for scratch disk space in the first place. 🧠

The Variables That Determine Your Approach

Not every setup responds to the same fix equally. A few factors shape which of the above methods will have the most impact:

• How full your primary drive is — if you're at 90%+ capacity, purging cache alone won't solve the underlying problem
• What application is triggering the error — Photoshop, Premiere, DaVinci Resolve, and Final Cut all manage scratch/cache differently
• Your RAM configuration — 8GB systems hit scratch limits far sooner than 32GB systems doing identical work
• Whether you work with video vs. still images — video editing generates substantially larger temporary files
• Drive type on your machine — an older HDD-based system experiences scratch disk bottlenecks differently than a machine with a fast NVMe SSD

A photographer running Photoshop on a MacBook with a nearly-full 256GB internal SSD is dealing with a fundamentally different constraint than a video editor on a Windows workstation with a dedicated scratch drive and 64GB of RAM. Both might see the same error message, but the practical fix — and how often the issue returns — will look quite different depending on their setup.