Install libgfortran4-s390x-cross by entering the following commands in the terminal:
sudo apt update sudo apt install libgfortran4-s390x-cross
Description:
Runtime library for GNU Fortran applications
Library needed for GNU Fortran applications linked against the shared library.
Homepage: http://gcc.gnu.org/
Version: 7.3.0-16ubuntu3cross1
Section: universe/devel