Missing engine content

I’ve moved my project from 4.6 first to 4.7 and then to 4.8, and tried from 4.6 to 4.8 directly.

Now, what I am getting on the Android App build is this:

App works when clicked OK.
Any ideas what to do about it?

And I can’t find things like Papersprite in my Engine content or anywhere. And I am not using paper anywhere as well.

Fixed it by migrating content to a totally new project.