I have been trying to export my character to 3ds Max 2017 and 2018 with the same results.  I want to build clothing and other stuff for the figure.  Every time I try and it doesn't matter what it is when I import I get the attached error.  It is very frustrating.

Relax..... don't pay attention to that and "Continue'
Trust Me.... That's Max stating it doesn't like that,
BUT....
You can work on the file and export it....."Just Fine."

I have (Ignored) that message for years.....
Let it go! 

ok thanks.