Save it as a .ma, maya changed the way that it's binary files .mb were saved. Edit: More information here: https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2018/ENU/Maya-WhatsNewPR/files/GUID-418024BF-0054-40BE-B334-BB0920D02101-htm.html
This is an old school hack.... Maya ascii files (.ma) have a header in them that defines what version of maya they are for. Save your .ma file as a copy, then right click and open it in a text editor like Notepad++. You'll see at the top of the file information like: //Maya ASCII 2016 scene//Name:…
I cant open it to save it as a Maya 2015 file. I am not at home right now and they only have Maya 2015 /: Thats why I am asking if someone else could do it for me