diff --git a/bin/MadGraph5_aMCatNLO/PLUGIN/CMS_CLUSTER/__init__.py b/bin/MadGraph5_aMCatNLO/PLUGIN/CMS_CLUSTER/__init__.py
index b790a4345abf..bfaca7a0f096 100644
--- a/bin/MadGraph5_aMCatNLO/PLUGIN/CMS_CLUSTER/__init__.py
+++ b/bin/MadGraph5_aMCatNLO/PLUGIN/CMS_CLUSTER/__init__.py
@@ -39,9 +39,9 @@
 try:
     from madgraph import MadGraph5Error
     import madgraph.various.misc as misc
-except Exception, error:
+except Exception as error:
     if __debug__:
-        print  str(error)
+        print(str(error))
     from internal import MadGraph5Error
     import internal.misc as misc
 
@@ -52,6 +52,14 @@
 multiple_try = misc.multiple_try
 pjoin = os.path.join
 
+import socket
+hostname = socket.gethostname()
+
+def singularityWraper():
+    if "lxplus" in hostname:
+        return '\nMY.WantOS = \"{}\"\n' % hostname.split(".")[0].replace("lxplus","el") # Following https://batchdocs.web.cern.ch/local/submit.html#os-selection-via-containers and simply using hostname 
+    elif "uscms" in hostname:
+        return '\nMY.WantOS = \"scl7\"\n' # Following https://batchdocs.web.cern.ch/local/submit.html#os-selection-via-containers and simply using hostname 
 
 def cleansubproc(subproc):
     subproc.terminate()
@@ -72,8 +80,8 @@ def __init__(self, *args, **opt):
             import htcondor
             self.schedd = htcondor.Schedd()
             self._action = htcondor.JobAction
-        except Exception, error:
-            raise ClusterManagmentError, 'could not import htcondor python API: \n%s' % error
+        except Exception as error:
+            raise ClusterManagmentError('could not import htcondor python API: \n%s' % error)
         self.hold_list = os.environ.get("CONDOR_RELEASE_HOLDCODES", "")
         self.max_shadows = os.environ.get("CONDOR_RELEASE_HOLDCODES_SHADOW_LIM", "")
         self.walltimes = os.environ.get("CONDOR_SET_MAXWALLTIMES", "")
@@ -225,12 +233,13 @@ def submit2(self, prog, argument=[], cwd=None, stdout=None, stderr=None,
                   %(requirement)s
                   getenv=True
                   %(leave_in_queue)s
+                  +REQUIRED_OS = "rhel7"
                   
                   +JobFlavour = "%(job_flavour)s"
                   
                   queue 1
                """
-        
+        text += singularityWraper() 
         if self.cluster_queue not in ['None', None]:
             requirement = 'Requirements = %s=?=True' % self.cluster_queue
         else:
@@ -248,6 +257,7 @@ def submit2(self, prog, argument=[], cwd=None, stdout=None, stderr=None,
             prog = os.path.join(cwd, prog)
         if argument:
             argument = 'Arguments = %s' % ' '.join([str(a) for a in argument])
+            #argument = '%s' % ' '.join([str(a) for a in argument])
         else:
             argument = ''
         # input/output file treatment
@@ -283,7 +293,7 @@ def submit2(self, prog, argument=[], cwd=None, stdout=None, stderr=None,
             cmd.append("-spool")
         a = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                              stdin=subprocess.PIPE)
-        output, _ = a.communicate(text % dico)
+        output, _ = a.communicate((text % dico).encode())
         #output = a.stdout.read()
         #Submitting job(s).
         #Logging submit event(s).
@@ -291,11 +301,12 @@ def submit2(self, prog, argument=[], cwd=None, stdout=None, stderr=None,
         if self.debug_print : logger.info( output )
             
         pat = re.compile("submitted to cluster (\d*)",re.MULTILINE)
+        output = output.decode()
         try:
             id = pat.search(output).groups()[0]
         except:
-            raise ClusterManagmentError, 'fail to submit to the cluster: \n%s' \
-                                                                        % output 
+            raise ClusterManagmentError('fail to submit to the cluster: \n%s' \
+                                                                        % output)
         self.submitted += 1
         self.submitted_ids.append(id)
         return id
@@ -310,8 +321,8 @@ def control_one_job(self, id):
         q = self.query([str(id)], ["JobStatus", "HoldReason"], lim=1)
         try:
             status = q[0]["JobStatus"]
-        except Exception, error:
-            raise ClusterManagmentError, 'could not retrieve job query:\n%s' % error
+        except Exception as error:
+            raise ClusterManagmentError('could not retrieve job query:\n%s' % error)
 
         s = self.status_map(status)
 
@@ -419,7 +430,6 @@ def __init__(self,*args, **opts):
 
         if self.temp_dir!=None:
             self.dorsync = True
-            #print "starting rsync"
           
             cwd = os.getcwd()
 
@@ -434,7 +444,6 @@ def __init__(self,*args, **opts):
             sock.close()    
             
             self.rsyncport = port
-            #print self.rsyncport
             
             rsynclog = os.path.join(cwd, 'rsyncd_%i.log' % self.rsyncport)
             rsynclock = os.path.join(cwd, 'rsyncd_%i.lock' % self.rsyncport)
@@ -447,11 +456,10 @@ def __init__(self,*args, **opts):
             rsyncsecrets = "%s:%s" % (self.rsyncuser,rsyncpasswd)
             rsyncsecretsfile = os.path.join(cwd, 'rsyncsecrets_%i' % self.rsyncport)
             secretsh = open(rsyncsecretsfile,'w')
-            os.chmod(rsyncsecretsfile, 0600)
+            os.chmod(rsyncsecretsfile, 0o600)
             secretsh.write(rsyncsecrets)
           
             os.environ["MADGRAPHRSYNCPASSWD_%i" % self.rsyncport] = rsyncpasswd
-            #print rsyncpasswd
 
             rsyncconf = """
               port = %(rsyncport)s
@@ -528,11 +536,11 @@ def submit(self, prog, argument=[], cwd=None, stdout=None, stderr=None, log=None
         try:
             id = output.split('>',1)[0].split('<')[1]
         except:
-            raise ClusterManagmentError, 'fail to submit to the cluster: \n%s' \
-                                                                        % output 
+            raise ClusterManagmentError('fail to submit to the cluster: \n%s' \
+                                                                        % output) 
         if not id.isdigit():
-            raise ClusterManagmentError, 'fail to submit to the cluster: \n%s' \
-                                                                        % output 
+            raise ClusterManagmentError('fail to submit to the cluster: \n%s' \
+                                                                        % output)
         self.submitted += 1
         self.submitted_ids.append(id)
         return id        
@@ -545,8 +553,6 @@ def submit2(self, prog, argument=[], cwd=None, stdout=None, stderr=None,
         """How to make one submission. Return status id on the cluster.
         NO SHARE DISK"""
 
-        #print "running lsf submit2"
-
         if cwd is None:
             cwd = os.getcwd()
         if not os.path.exists(prog):
@@ -660,11 +666,11 @@ def submit2(self, prog, argument=[], cwd=None, stdout=None, stderr=None,
         try:
             id = output.split('>',1)[0].split('<')[1]
         except:
-            raise ClusterManagmentError, 'fail to submit to the cluster: \n%s' \
-            % output
+            raise ClusterManagmentError('fail to submit to the cluster: \n%s' \
+            % output)
         if not id.isdigit():
-            raise ClusterManagmentError, 'fail to submit to the cluster: \n%s' \
-            % output
+            raise ClusterManagmentError('fail to submit to the cluster: \n%s' \
+            % output)
         self.submitted += 1
         self.submitted_ids.append(id)
         return id         
diff --git a/bin/MadGraph5_aMCatNLO/Utilities/source_condor.sh b/bin/MadGraph5_aMCatNLO/Utilities/source_condor.sh
index 99f18d3fb78b..8ee2d7d7bd3e 100644
--- a/bin/MadGraph5_aMCatNLO/Utilities/source_condor.sh
+++ b/bin/MadGraph5_aMCatNLO/Utilities/source_condor.sh
@@ -1,23 +1,14 @@
-#! /bin/bash
+#!/bin/bash
 
 # HTCondor python bindings are lost after cmsenv/scram
-# unless PYTHONPATH is set including its location
-# Workaround: Include original location in the path
-# if not there already.
-PYTHON_BINDINGS="$(python -c 'import htcondor; import os; print os.path.dirname(htcondor.__path__[0])' 2>/dev/null)"
+PYTHON_BINDINGS="$(python -c 'import htcondor; import os; print(os.path.dirname(htcondor.__path__[0]))' 2>/dev/null)"
 if [ -z "$PYTHON_BINDINGS" ]; then
-    echo "Error: Could not find htcondor python binding (htcondor.so), please include the directory in PYTHONPATH."
-    exit 1
+if [ -d $CMSSW_BASE/venv ];
+then 
+  echo "venv exists"
 else
-  if [ -n "$PYTHONPATH" ]; then
-      case ":$PYTHONPATH:" in
-        *:$PYTHON_BINDINGS:*) :
-        ;;
-        *) export PYTHONPATH="$PYTHON_BINDINGS:$PYTHONPATH"
-        ;;
-      esac
-  else
-      export PYTHONPATH="$PYTHON_BINDINGS"
-  fi
-  export PYTHON_BINDINGS="$PYTHON_BINDINGS"
+  scram-venv
+  cmsenv
+  pip3 install htcondor --upgrade #FIXME need better way to interface HTCondor Python API for Python3.9
+fi
 fi
diff --git a/bin/MadGraph5_aMCatNLO/gridpack_generation.sh b/bin/MadGraph5_aMCatNLO/gridpack_generation.sh
index fd9b9d61c8f3..8a655dd24ea6 100755
--- a/bin/MadGraph5_aMCatNLO/gridpack_generation.sh
+++ b/bin/MadGraph5_aMCatNLO/gridpack_generation.sh
@@ -42,7 +42,7 @@ make_tarball () {
     if [ -e merge.pl ]; then
         EXTRA_TAR_ARGS+="merge.pl "
     fi
-    XZ_OPT="$XZ_OPT" tar -cJpsf ${PRODHOME}/${name}_${scram_arch}_${cmssw_version}_tarball.tar.xz mgbasedir process runcmsgrid.sh gridpack_generation*.log InputCards $EXTRA_TAR_ARGS
+    XZ_OPT="$XZ_OPT" tar -cJpf ${PRODHOME}/${name}_${scram_arch}_${cmssw_version}_tarball.tar.xz mgbasedir process runcmsgrid.sh gridpack_generation*.log InputCards $EXTRA_TAR_ARGS
 
     echo "Gridpack created successfully at ${PRODHOME}/${name}_${scram_arch}_${cmssw_version}_tarball.tar.xz"
     echo "End of job"
@@ -176,7 +176,7 @@ make_gridpack () {
       wget --no-check-certificate ${MGSOURCE}
       tar xzf ${MG}
       rm "$MG"
-    
+
       #############################################
       #Apply any necessary patches on top of official release
       #############################################
@@ -184,6 +184,7 @@ make_gridpack () {
       cd $MGBASEDIRORIG
       cat $PRODHOME/patches/*.patch | patch -p1
       cp -r $PRODHOME/PLUGIN/CMS_CLUSTER/ PLUGIN/ 
+      cp $PRODHOME/PLUGIN/*.sh/ PLUGIN/ 
       # Intended for expert use only!
       if ls $CARDSDIR/${name}*.patch; then
         echo "    WARNING: Applying custom user patch. I hope you know what you're doing!"
@@ -238,7 +239,6 @@ make_gridpack () {
           echo "set cluster_status_update $long_wait $short_wait" >> mgconfigscript
           echo "set cluster_nb_retry $n_retries" >> mgconfigscript
           echo "set cluster_retry_wait 300" >> mgconfigscript
-          #echo "set cluster_local_path `${LHAPDFCONFIG} --datadir`" >> mgconfigscript 
           if [[ ! "$RUNHOME" =~ ^/afs/.* ]]; then
               echo "local path is not an afs path, batch jobs will use worker node scratch space instead of afs"
               #*FIXME* broken in mg_amc 2.4.0
@@ -317,6 +317,7 @@ make_gridpack () {
 	  cp -r $PRODHOME/PLUGIN/MadSTR $MGBASEDIRORIG/PLUGIN/ # copy plugin 
           ./$MGBASEDIRORIG/bin/mg5_aMC --mode=MadSTR ${name}_proc_card.dat # run invoking MadSTR plugin
       fi
+      cat ${name}_proc_card.dat
 	
       is5FlavorScheme=0
       if tail -n 20 $LOGFILE | grep -q -e "^p *=.*b\~.*b" -e "^p *=.*b.*b\~"; then 
@@ -728,6 +729,7 @@ fi
 
 #catch unset variables
 set -u
+unset PERL5LIB
 
 if [ -z ${carddir} ]; then
     echo "Card directory not provided"
@@ -772,7 +774,7 @@ if [[ `uname -a` == *"lxplus"* ]]; then
 fi
 
 LOGFILE=${RUNHOME}/${name}.log
-LOGFILE_NAME=${LOGFILE/.log/}
+LOGFILE_NAME=${RUNHOME}/${name}
 
 # where to search for datacards, that have to follow a naming code: 
 #   ${name}_proc_card_mg5.dat