Compilation error on Mac OS 10.14.5 after installing Pythia & Delphes

Dear MG group:

 I am asking a question about the latest MG on Mac OS 10.14.5. MG runs well before installing Pythia & Delphes. After the installation, I saw the following compilation errors.

generate_events run_01
 Traceback (most recent call last):
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/interface/extended_cmd.py", line 1541, in onecmd
     return self.onecmd_orig(line, **opt)
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/interface/extended_cmd.py", line 1490, in onecmd_orig
     return func(arg, **opt)
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/interface/madevent_interface.py", line 2471, in do_generate_events
     self.run_generate_events(switch_mode, args)
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/interface/common_run_interface.py", line 7080, in new_fct
     original_fct(obj, *args, **opts)
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/interface/madevent_interface.py", line 2510, in run_generate_events
     self.exec_cmd('survey %s %s' % (self.run_name,' '.join(args)),
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/interface/extended_cmd.py", line 1570, in exec_cmd
     stop = Cmd.onecmd_orig(current_interface, line, **opt)
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/interface/extended_cmd.py", line 1490, in onecmd_orig
     return func(arg, **opt)
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/interface/madevent_interface.py", line 3363, in do_survey
     jobs, P_zero_result = ajobcreator.launch()
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/madevent/gen_ximprove.py", line 193, in launch
     self.cmd.compile(['madevent'], cwd=Pdir)
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/interface/extended_cmd.py", line 1634, in compile
     return misc.compile(nb_core=self.options['nb_core'], *args, **opts)
   File "/Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/madgraph/various/misc.py", line 546, in compile
     raise MadGraph5Error(error_text)
 madgraph.MadGraph5Error: A compilation Error occurs when trying to compile /Users/xialigang/workarea/softwares/MG5_aMC_v2_8_2/bin/pp2tt/ SubProcesses/P1_gg_ttx.
 The compilation fails with the following output message:
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c driver.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c myamp.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c genps.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c unwgt.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c setcuts.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c get_color.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c cuts.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c cluster.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c reweight.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c initcluster.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c addmothers.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c setscales.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c dummy_fct.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c auto_dsig.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c auto_dsig1.f -I../../Source/
     gfortran -O -w -fbounds-check -fPIC -ffixed-line-length-132 -w -c matrix1.f -I../../Source/
     gfortran -o madevent driver.o myamp.o genps.o unwgt.o setcuts.o get_color.o cuts.o cluster.o reweight.o initcluster.o addmothers.o setscales.o idenparts.o dummy_fct.o auto_dsig.o auto_dsig1.o matrix1.o -L../../lib/ -ldhelas -ldsample -lmodel -lgeneric -lpdf - lcernlib -lbias -lc++ -mmacosx-version-min=10.8
   ld: warning: object file (driver.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (myamp.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (genps.o) was built for newer OSX version (11.14) than being linked (10.8)
     ld: warning: object file (unwgt.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (setcuts.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (get_color.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (cuts.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (reweight.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (cluster.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (initcluster.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (addmothers.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (setscales.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (idenparts.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (dummy_fct.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (auto_dsig.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (auto_dsig1.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (matrix1.o) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libdsample.a(DiscreteSampler.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(alfas_functions.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libbias.a(dummy.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libdhelas.a(aloha_functions.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(basecode.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(dgauss.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(kin_functions.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libdhelas.a(FFV1_0.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libdhelas.a(FFV1_1.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libdhelas.a(FFV1_2.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(getissud.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(invarients.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libpdf.a(opendata.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(open_file.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libpdf.a(pdg2pdf.o)) was built for newer OSX version (10.14) than being linked (10.8)
    ld: warning: object file (../../lib//libmodel.a(printout.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libdsample.a(dsample.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libdsample.a(ranmar.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(rw_events.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(readgrid.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(run_printout.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libmodel.a(rw_para.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(setrun.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(transpole.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libmodel.a(couplings.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libdhelas.a(VVV1P0_1.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(ran1.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libdsample.a(StringCast.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libmodel.a(couplings1.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libmodel.a(couplings2.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libpdf.a(Ctq6Pdf.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libcernlib.a(dlsqp2.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libpdf.a(PhotonFlux.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libgeneric.a(pawgraphs.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libpdf.a(pdfwrap.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libpdf.a(pdf.o)) was built for newer OSX version (10.14) than being linked (10.8)
     ld: warning: object file (../../lib//libpdf.a(NNPDFDriver.o)) was built for newer OSX version (10.14) than being linked (10.8)
     Undefined symbols for architecture x86_64:
       "_epa_lepton_", referenced from:
           _fdist_ in libpdf.a(pdf.o)
     ld: symbol(s) not found for architecture x86_64
     collect2: error: ld returned 1 exit status
     make: *** [madevent] Error 1

I was generating some t t~ events for testing.

 generate p p > t t~
 output pp2tt
 launch

Do you have any ideas? Let me know if you need more information.

Best regards,
Ligang