I just saw a File Input message type for the first time today and this is the only community article I could find that seemed relevant.
It appears on the validation run messaging after we tried to publish to the Gallery.
Alteryx Workflow Input Files to be uploaded...0 records were read from "<filename>" (limit reached)
Does this mean that the server capacity has reached it's limit?
I couldn't find anything to confirm this, so I thought I'd add a softball question for it 
Thanks,
MJ