Is there a way to automatically clean disk cache before each render?
I got once in a while random frames in videos after rendering, frames are from past renders and from completly different projects. After making purge renders looks ok, but this is quite annoying to do that manually all the time. This happend on 2014 and 2015 version, I'm not sure about 2017 version as it's available for too short.
There is not a way to do that automatically. Your best bet is to do it yourself before starting a render. That being said, CC 2017 has fixed a number of caching issues people have been having, so I would suggest giving it a try when you can. Remember, you can install CC 2017 alongside CC 2015.3 and CC 2015. (Don't forget to click into the "Advanced Options" in the CC app after you click "Update" to turn off the option to remove older versions.)