On my sandbox I have winter 18 now.
I have played around to see all new community features, and suddenly I realize that the component list does not have any custom components:
As you can see - no section Custom Components
Also - my existing custom components (that where added before the Winter18 upgrade) exist in current pages, but when I click on any of them to see and edit their properties, I get the following error message:
We had trouble processing the request. We've reported the problem to Customer Support with error ID: 972428812
Last thing - I have checked my production org, and over there I can see and manage my custom component:
Is this a bug or am I doing something wrong?