There was resent bug in Photoshop where Photoshop kept filling users scratch space on some machines. I believe it has been fixed. Do you have all update installed? Current CC 2017 is version CC 2017.1.1
I did update Photoshop to the latest version and tried again with a normal sized file to duplicate one layer and it kept saying scratch disk full.. I nearly emptied my hard drive... I wonder if Photoshop does not purge the scratch disk after an update. I thought about uninstalling photoshop all together and reinstalling but I'm afraid of losing all my presets.
By what I read on the thread it seems it hasn't been fixed
A user I work with is having the same issue, or at least a similar issue. Win 7, latest version of PS. When opening a project and clicking on a tool, the message pops up. Or dragging an existing project from the desktop: same thing. The hard drive has 146gb free.
Why is this happening?
I got a response from Adobe. They said to Update Photoshop to the latest version and then reset the preferences once.
I did that and the problem seems to have gone away.
Hope this helps!