If you have a different partition on your Primary drive with some space left or have a different drive connected to your computer, You could change the scratch disk to a different drive from "Scratch disk preferences". Take a look at the solution in this discussion Scratch disk full and cannot open photoshop to fix it... and let us know if that helps.
Make sure that you updated to Photoshop 2017.1.1. (released today).
This update includes a fix for a scratch space issue.
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It is good that bug has been fixed it would be even better if other reported bugs were also fixed. So users like me can get off of CC 2014. Adobe feedback site states that work is in progress for I bug I reported. Its been in Progress in CC 2015.5 in CC 2017 and is still in progress I guess in CC 2017.1.1 progress seems to be stalled IMO. I have reported other bugs that have been in Photoshop forever and will most likely remain in Photoshop till its life-cycle end. IMO Bugs will eventually kill Photoshop but without competition that will not be within my life time. Its Photoshop till the end of me....