undefined reference to `main'

[nascimentoafd]

Hi There,
I am trying to compile specfem2d and I am getting this message:

building xcheck_quality_external_mesh

/opt/ohpc/pub/compiler/gcc/9.4.0/bin/gfortran -g -O2 -std=f2008 -fimplicit-none -frange-check -fmax-errors=10 -pedantic -pedantic-errors -Waliasing -Wampersand -Wcharacter-truncation -Wline-truncation -Wsurprising -Wno-tabs -Wunderflow -ffpe-trap=invalid,zero,overflow -Wunused -O3 -finline-functions -o bin/xcheck_quality_external_mesh obj/check_quality_external_mesh.aux.o obj/shared_par.shared_module.o obj/define_shape_functions.shared.o obj/exit_mpi.shared.o obj/parallel.shared.o obj/read_parameter_file.mesh.o obj/read_value_parameters.shared.o obj/read_material_table.mesh.o obj/read_interfaces_file.mesh.o obj/read_regions.mesh.o obj/param_reader.cc.o
/lib/../lib64/crt1.o: In function _start': (.text+0x24): undefined reference to main'
collect2: error: ld returned 1 exit status
make: *** [src/auxiliaries/rules.mk:136: bin/xcheck_quality_external_mesh] Error 1

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Any thoughts on this might be? The same error shows up when using MPFI=mpif90 in the configure option (even using the full path). I am quite new at using specfem, have looked into the documentation but could not get it compiled. Any help is appreciated.
Cheers
Aderson