Maya ART Problem

Could not save file: X:/Program Files/Unreal Engine/4.0/Engine/Extras/Maya_AnimationRiggingTools/MayaTools/General/ART/Projects/Sample/ExportFiles/tesst_Export.mb not a valid file.
File may exist already and be marked as read only. Aborting operation.

This shows up whenever I try to build a character.

I apologize, did not mean to duplicate.

This is a known issue apparently and is being addressed:

See this thread.