I was trying to use the Compare Files tool with two PDFs, but when I clicked "Compare" I was prompted with this error "Expected a dict object." (See CleanShot 2020-09-17 at 16.16.02) Afterward the Acrobat application ceased to function normally and I had to restart. After attempting to open one of the files, it became clear that the PDF was damaged in some way. I'm not able to attach the damaged PDF here, but I'm sure it's easy to find one to reproduce the error.

A more helpful error message in the Compare Files tool would be one that indicates which of the files is damaged, like the one shown here when you open the problematic file alone. (See CleanShot 2020-09-17 at 16.57.22)

OS: macOS Version 10.15.5 (19F101)
Acrobat Build: 20.12.20043.396433