Can render hair in viewport only

I have these characters that I set up with hair. They render just fine in the viewpoint with cycles but when I try to render the images Blender freezes or crash. I tried 2.81 and 2.82a. Same thing. The children are set to the same amount for preview and render. Any idea?

EDIT: out of 12 characters, the one that don’t work are the female with long hair. Still doesn’t fix the problem but it’a a clue.