Maya character skeleton export errors

Hey guys,
I was hoping you could help me out on a problem we’re having for exporting our characters animations into UE4.
For some reason when I first exported the animations they all worked fine but once I made a correction and tried to re export them a SKIN DEFINITION error appears for most of my character’s mesh and when I put this into UE4 the character does not appear.
PLEASE HELP!!
I’m using the classic exporting workflow. Selecting all joint hierarchy, baking the animations. Once this is done I select the root and all the character’s mesh and I export selected.
This is when the error occurs but makes no sense.