All the time when gfortran is bumped version, all fortran modules (file with .mod extensions) in other packages must be recompiled because module definitions are changed in the new compiler gfortran. Example : netcdf-fortran is broke currently if one try compile this code ==== module test use netcdf end module test ==== gfortran -I/usr/include -c test.f90 test.f90:2.7: use netcdf 1 Fatal Error: Cannot read module file 'netcdf.mod' opened at (1), because it was created by a different version of GNU Fortran