[CCleaner v5.55.7108 (64-Bit) upgrade error on Windows 10]

Worked, failed, works again. Nothing was intentionally changed on my end so I'm inclined to guess it is on the Piriform's cloud side. 

By the way, the updater, based on my experience, is not automatic. You have to get involved in releasing an update. My preference has been to not directly use 3rd party update managers but to instead use the application's own update process or the author's website. 

Not every application/product is tracked by ccleaner's updater. I appreciate the new feature but it's not going to solve all updating concerns or world hunger. 

[CCleaner v5.55.7108 (64-Bit) upgrade error on Windows 10]

I have the same problem. Earlier in the day it was working well and due to the report updated a few applications.