[gmx-users] Fatal error: A coordinate in file box.gro does not contain a '.'

[Edjan Silva]

This error occurred while typing the following command:

gmx solvate -cp box.gro -cs spc216.gro -o box_sol.gro -p topol.top

basically what happened was that all the coordinates that were in my
box.gro file were replaced by the word "-nan".

I've never seen anything like this. can anyone tell why this error occurs?