Maya file cannot open correctly in older version


Hello guys,
I have a .ma file which not from me, but I guess it was saved in 2018.6, cause I saw the version 2018ff09 in ma file. At the first, i can not open it with 2018, got a warning like

unkonwn file version 2018ff09

After I updated my maya to 2018.6, I am still got an

error: file: //xxxxxxx/xx/x (my file path) line 8: keyerror: file c:\Program Files\Autodesk\Maya2018\bin\\os/py line 425: aaaa//

what in the line 8 from my file is:

-typ “mayaBinary” “$aaaa/…”;

(the path is start with $ is my mb reference file loacation, same with the error above, the last aaaa)

Anyone has some ideas why this happen?
Thanks in advance!