frank pilot
If you receive an error message that indicates 'scratch disks are full' it often means: drives used by Photoshop as scratch disks are running out of storage space and that more free space is required to perform a particular task. Some general information and solutions can be found at the following page: https://helpx.adobe.com/photoshop/kb/troubleshoot-scratch-disk-is-full.html
From my experience, one of the most common reasons that users experience this error is related to document size/resolution. Generally, the problem occurs when the user is creating a New Document (using the File > New command). Users will often [accidentally] set the units to inches or centimeters (when they actually wanted pixels) and then continue creating the document before they catch the mistake. (See the screen capture below.) This will create a very large canvas and will often cause the aforementioned "scratch disks are full" error. Take care when creating new documents that you are using the correct units of measure.
