diff --git a/Configuration/Applications/python/ConfigBuilder.py b/Configuration/Applications/python/ConfigBuilder.py
index ecdac265279bd..5cfa3530d8d6b 100644
--- a/Configuration/Applications/python/ConfigBuilder.py
+++ b/Configuration/Applications/python/ConfigBuilder.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 from __future__ import print_function
 __version__ = "$Revision: 1.19 $"
diff --git a/Configuration/Applications/python/Options.py b/Configuration/Applications/python/Options.py
index 705804c00df52..0c5e39fe1f44c 100644
--- a/Configuration/Applications/python/Options.py
+++ b/Configuration/Applications/python/Options.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 # A Pyrelval Wrapper
 
diff --git a/Configuration/Applications/python/cmsDriverOptions.py b/Configuration/Applications/python/cmsDriverOptions.py
index c621c64673a7b..d7db1e394ded9 100755
--- a/Configuration/Applications/python/cmsDriverOptions.py
+++ b/Configuration/Applications/python/cmsDriverOptions.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 # A Pyrelval Wrapper
 
diff --git a/Configuration/Applications/scripts/cmsDriver.py b/Configuration/Applications/scripts/cmsDriver.py
index 210656b6090eb..a99a87a924f7e 100755
--- a/Configuration/Applications/scripts/cmsDriver.py
+++ b/Configuration/Applications/scripts/cmsDriver.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 # A Pyrelval Wrapper
 
diff --git a/Configuration/DataProcessing/python/GetScenario.py b/Configuration/DataProcessing/python/GetScenario.py
index 8e7cd004ee8dd..f357e61c6e083 100644
--- a/Configuration/DataProcessing/python/GetScenario.py
+++ b/Configuration/DataProcessing/python/GetScenario.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _GetScenario_
 
diff --git a/Configuration/DataProcessing/python/Impl/AlCa.py b/Configuration/DataProcessing/python/Impl/AlCa.py
index 11cac082532bf..f460660712f54 100644
--- a/Configuration/DataProcessing/python/Impl/AlCa.py
+++ b/Configuration/DataProcessing/python/Impl/AlCa.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _AlCa_
 
diff --git a/Configuration/DataProcessing/python/Impl/AlCaLumiPixels.py b/Configuration/DataProcessing/python/Impl/AlCaLumiPixels.py
index 03288b86bace7..eb30b5af1fe4c 100644
--- a/Configuration/DataProcessing/python/Impl/AlCaLumiPixels.py
+++ b/Configuration/DataProcessing/python/Impl/AlCaLumiPixels.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _AlCaLumiPixels_
 
diff --git a/Configuration/DataProcessing/python/Impl/AlCaP0.py b/Configuration/DataProcessing/python/Impl/AlCaP0.py
index b66768b216c49..97793567caeb5 100644
--- a/Configuration/DataProcessing/python/Impl/AlCaP0.py
+++ b/Configuration/DataProcessing/python/Impl/AlCaP0.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _AlCaP0_
 
diff --git a/Configuration/DataProcessing/python/Impl/AlCaPhiSymEcal.py b/Configuration/DataProcessing/python/Impl/AlCaPhiSymEcal.py
index a865721330751..c8185b3f1d603 100644
--- a/Configuration/DataProcessing/python/Impl/AlCaPhiSymEcal.py
+++ b/Configuration/DataProcessing/python/Impl/AlCaPhiSymEcal.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _AlCaPhiSymEcal_
 
diff --git a/Configuration/DataProcessing/python/Impl/AlCaTestEnable.py b/Configuration/DataProcessing/python/Impl/AlCaTestEnable.py
index 6cadd89b23b78..ba46ff376c65d 100644
--- a/Configuration/DataProcessing/python/Impl/AlCaTestEnable.py
+++ b/Configuration/DataProcessing/python/Impl/AlCaTestEnable.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _AlCaTestEnable_
 
diff --git a/Configuration/DataProcessing/python/Impl/DataScouting.py b/Configuration/DataProcessing/python/Impl/DataScouting.py
index 8fd9eb8f2de93..f964ccd37a70d 100644
--- a/Configuration/DataProcessing/python/Impl/DataScouting.py
+++ b/Configuration/DataProcessing/python/Impl/DataScouting.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _DataScouting_
 
diff --git a/Configuration/DataProcessing/python/Impl/HeavyIons.py b/Configuration/DataProcessing/python/Impl/HeavyIons.py
index 0508d0f8abd54..d46db1d1c676f 100644
--- a/Configuration/DataProcessing/python/Impl/HeavyIons.py
+++ b/Configuration/DataProcessing/python/Impl/HeavyIons.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _HeavyIons_
 
diff --git a/Configuration/DataProcessing/python/Impl/HeavyIonsEra_Run2_2018.py b/Configuration/DataProcessing/python/Impl/HeavyIonsEra_Run2_2018.py
index f37c6225d6d5c..2aa4ff00d961e 100644
--- a/Configuration/DataProcessing/python/Impl/HeavyIonsEra_Run2_2018.py
+++ b/Configuration/DataProcessing/python/Impl/HeavyIonsEra_Run2_2018.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _HeavyIonsEra_Run2_2018_
 
diff --git a/Configuration/DataProcessing/python/Impl/HeavyIonsEra_Run2_HI.py b/Configuration/DataProcessing/python/Impl/HeavyIonsEra_Run2_HI.py
index a567fff2e7048..e3b2f7b25ecb1 100644
--- a/Configuration/DataProcessing/python/Impl/HeavyIonsEra_Run2_HI.py
+++ b/Configuration/DataProcessing/python/Impl/HeavyIonsEra_Run2_HI.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _HeavyIonsEra_Run2_HI_
 
diff --git a/Configuration/DataProcessing/python/Impl/Test.py b/Configuration/DataProcessing/python/Impl/Test.py
index 20bc4b38d1daf..fe28fb26ff85e 100644
--- a/Configuration/DataProcessing/python/Impl/Test.py
+++ b/Configuration/DataProcessing/python/Impl/Test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _Test_
 
diff --git a/Configuration/DataProcessing/python/Impl/__init__.py b/Configuration/DataProcessing/python/Impl/__init__.py
index 09e56ef45508d..c64cbb575bcfa 100644
--- a/Configuration/DataProcessing/python/Impl/__init__.py
+++ b/Configuration/DataProcessing/python/Impl/__init__.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _Impl_
 
diff --git a/Configuration/DataProcessing/python/Impl/cosmics.py b/Configuration/DataProcessing/python/Impl/cosmics.py
index 2546ba55e2acf..0d00c1a5a2666 100644
--- a/Configuration/DataProcessing/python/Impl/cosmics.py
+++ b/Configuration/DataProcessing/python/Impl/cosmics.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmics_
 
diff --git a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2016.py b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2016.py
index ee84f03b88ec8..27526ec8d0b93 100644
--- a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2016.py
+++ b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2016.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsEra_Run2_2016_
 
diff --git a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2017.py b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2017.py
index cdba16819b1ef..9946b56997b79 100644
--- a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2017.py
+++ b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2017.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsEra_Run2_2017_
 
diff --git a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2018.py b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2018.py
index 33b95cd056699..ed50dfa0f6bf3 100644
--- a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2018.py
+++ b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_2018.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsEra_Run2_2018_
 
diff --git a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_25ns.py b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_25ns.py
index a637e216613a0..5329cde188aee 100644
--- a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_25ns.py
+++ b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_25ns.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsEra_Run2_25ns_
 
diff --git a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_50ns.py b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_50ns.py
index d7faf0907ef78..26ba03a1f370e 100644
--- a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_50ns.py
+++ b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run2_50ns.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsEra_Run2_50ns_
 
diff --git a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run3.py b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run3.py
index 305ad96879fee..fff4dddd041fb 100644
--- a/Configuration/DataProcessing/python/Impl/cosmicsEra_Run3.py
+++ b/Configuration/DataProcessing/python/Impl/cosmicsEra_Run3.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsEra_Run3_
 
diff --git a/Configuration/DataProcessing/python/Impl/cosmicsHybrid.py b/Configuration/DataProcessing/python/Impl/cosmicsHybrid.py
index 23348298c54d7..d783b0dc17075 100644
--- a/Configuration/DataProcessing/python/Impl/cosmicsHybrid.py
+++ b/Configuration/DataProcessing/python/Impl/cosmicsHybrid.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsHybrid_
 
diff --git a/Configuration/DataProcessing/python/Impl/cosmicsHybridEra_Run2_2018.py b/Configuration/DataProcessing/python/Impl/cosmicsHybridEra_Run2_2018.py
index 3cdae74b6cd5f..a1212697a485c 100644
--- a/Configuration/DataProcessing/python/Impl/cosmicsHybridEra_Run2_2018.py
+++ b/Configuration/DataProcessing/python/Impl/cosmicsHybridEra_Run2_2018.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsHybridEra_Run2_2018_
 
diff --git a/Configuration/DataProcessing/python/Impl/hcalnzs.py b/Configuration/DataProcessing/python/Impl/hcalnzs.py
index dfcec239d9551..f280f901d1405 100644
--- a/Configuration/DataProcessing/python/Impl/hcalnzs.py
+++ b/Configuration/DataProcessing/python/Impl/hcalnzs.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _hcalnzs_
 
diff --git a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2016.py b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2016.py
index 2751b10a02e55..df0bf3969c925 100644
--- a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2016.py
+++ b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2016.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _hcalnzsEra_Run2_2016_
 
diff --git a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2017.py b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2017.py
index 716b7b5815b24..8fa79c699a296 100644
--- a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2017.py
+++ b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2017.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _hcalnzsEra_Run2_2017_
 
diff --git a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018.py b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018.py
index ed99252a59dcc..75ae3007bedf9 100644
--- a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018.py
+++ b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _hcalnzsEra_Run2_2018_
 
diff --git a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018_highBetaStar.py b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018_highBetaStar.py
index 65a96b86bac32..0df7962610feb 100644
--- a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018_highBetaStar.py
+++ b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018_highBetaStar.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _hcalnzsEra_Run2_2018_highBetaStar_
 
diff --git a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018_pp_on_AA.py b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018_pp_on_AA.py
index fd65329d1386c..73cc527105da4 100644
--- a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018_pp_on_AA.py
+++ b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_2018_pp_on_AA.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _hcalnzsEra_Run2_2018_pp_on_AA_
 
diff --git a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_25ns.py b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_25ns.py
index 43bd7d4d05b01..a262ba7c5d953 100644
--- a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_25ns.py
+++ b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run2_25ns.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _hcalnzsEra_Run2_25ns_
 
diff --git a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run3.py b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run3.py
index 6bb0bff0d0ff9..14c0a1bbd0f52 100644
--- a/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run3.py
+++ b/Configuration/DataProcessing/python/Impl/hcalnzsEra_Run3.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _hcalnzsEra_Run3_
 
diff --git a/Configuration/DataProcessing/python/Impl/pp.py b/Configuration/DataProcessing/python/Impl/pp.py
index 7fa7821ea4e36..93056b7fc6be9 100644
--- a/Configuration/DataProcessing/python/Impl/pp.py
+++ b/Configuration/DataProcessing/python/Impl/pp.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _pp_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016.py
index b278e46444282..2ebacfc17137b 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2016_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016_pA.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016_pA.py
index bc2a6827a4173..04f6918e2eea5 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016_pA.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016_pA.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2016_pA_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016_trackingLowPU.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016_trackingLowPU.py
index d707b57c8db3c..5befd9fb13aaa 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016_trackingLowPU.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2016_trackingLowPU.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2016_trackingLowPU_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017.py
index c50c24b7d7309..036c2baeee36b 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2017_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_ppRef.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_ppRef.py
index 8ec59419246ea..c438c33aee07a 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_ppRef.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_ppRef.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2017_ppRef_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_pp_on_XeXe.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_pp_on_XeXe.py
index ffd699efd809b..c475b88d8ef76 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_pp_on_XeXe.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_pp_on_XeXe.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2017_pp_on_XeXe_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_trackingLowPU.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_trackingLowPU.py
index 7eae267ec511d..81f75f4a33ee1 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_trackingLowPU.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_trackingLowPU.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2017_trackingLowPU_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_trackingOnly.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_trackingOnly.py
index ac0b9fa1c11c9..5db143a015302 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_trackingOnly.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2017_trackingOnly.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2017_trackingOnly
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018.py
index 9c9ad7ee896e0..4940ae7139bb0 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2018_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018_highBetaStar.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018_highBetaStar.py
index 1cff6ddf8203e..c6592ed4ed02c 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018_highBetaStar.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018_highBetaStar.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2018_highBetaStar_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018_pp_on_AA.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018_pp_on_AA.py
index 1f38e3663a1dd..2c4f738522da9 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018_pp_on_AA.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_2018_pp_on_AA.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2018_pp_on_AA_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_25ns.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_25ns.py
index bd5a85a9c8266..7c48cf10d9665 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_25ns.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_25ns.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_25ns_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run2_50ns.py b/Configuration/DataProcessing/python/Impl/ppEra_Run2_50ns.py
index 6560311d0ff51..1df74731c028a 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run2_50ns.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run2_50ns.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_50ns_
 
diff --git a/Configuration/DataProcessing/python/Impl/ppEra_Run3.py b/Configuration/DataProcessing/python/Impl/ppEra_Run3.py
index e96f9d0514db9..088818ddf2451 100644
--- a/Configuration/DataProcessing/python/Impl/ppEra_Run3.py
+++ b/Configuration/DataProcessing/python/Impl/ppEra_Run3.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run3_
 
diff --git a/Configuration/DataProcessing/python/Impl/preprodmc.py b/Configuration/DataProcessing/python/Impl/preprodmc.py
index da8e181405577..22c1a6d00e500 100644
--- a/Configuration/DataProcessing/python/Impl/preprodmc.py
+++ b/Configuration/DataProcessing/python/Impl/preprodmc.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _preprodmc_
 
diff --git a/Configuration/DataProcessing/python/Impl/prodmc.py b/Configuration/DataProcessing/python/Impl/prodmc.py
index de80706229c43..8a62c83461847 100644
--- a/Configuration/DataProcessing/python/Impl/prodmc.py
+++ b/Configuration/DataProcessing/python/Impl/prodmc.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _prodmc_
 
diff --git a/Configuration/DataProcessing/python/Impl/relvalgen.py b/Configuration/DataProcessing/python/Impl/relvalgen.py
index 0239f8cc482da..f5b286feda6c7 100644
--- a/Configuration/DataProcessing/python/Impl/relvalgen.py
+++ b/Configuration/DataProcessing/python/Impl/relvalgen.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _relvalgen_
 
diff --git a/Configuration/DataProcessing/python/Impl/relvalmc.py b/Configuration/DataProcessing/python/Impl/relvalmc.py
index 8c3bce7b635f3..4c48bf5611a4b 100644
--- a/Configuration/DataProcessing/python/Impl/relvalmc.py
+++ b/Configuration/DataProcessing/python/Impl/relvalmc.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _relvalmc_
 
diff --git a/Configuration/DataProcessing/python/Impl/relvalmcfs.py b/Configuration/DataProcessing/python/Impl/relvalmcfs.py
index 026750b97efb5..c0bb8d53c15c6 100644
--- a/Configuration/DataProcessing/python/Impl/relvalmcfs.py
+++ b/Configuration/DataProcessing/python/Impl/relvalmcfs.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _relvalmcfs_
 
diff --git a/Configuration/DataProcessing/python/Impl/trackingOnly.py b/Configuration/DataProcessing/python/Impl/trackingOnly.py
index dc2f2fb270ac8..211f15c73e98d 100644
--- a/Configuration/DataProcessing/python/Impl/trackingOnly.py
+++ b/Configuration/DataProcessing/python/Impl/trackingOnly.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _trackingOnly_
 
diff --git a/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2017.py b/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2017.py
index 99c71bbe192ed..be19d32548d6d 100644
--- a/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2017.py
+++ b/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2017.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _trackingOnlyEra_Run2_2017
 
diff --git a/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018.py b/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018.py
index 35e137a19c70c..07b3716c25d8c 100644
--- a/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018.py
+++ b/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _trackingOnlyEra_Run2_2018
 
diff --git a/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018_highBetaStar.py b/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018_highBetaStar.py
index 3147fc0999de1..c1f46cc7fd897 100644
--- a/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018_highBetaStar.py
+++ b/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018_highBetaStar.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _trackingOnlyEra_Run2_2018_highBetaStar
 
diff --git a/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018_pp_on_AA.py b/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018_pp_on_AA.py
index f602e8d7388b4..1335cd3841a2d 100644
--- a/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018_pp_on_AA.py
+++ b/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run2_2018_pp_on_AA.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _trackingOnlyEra_Run2_2018_pp_on_AA
 
diff --git a/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run3.py b/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run3.py
index 6379fde103f40..302e46d7c4ca7 100644
--- a/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run3.py
+++ b/Configuration/DataProcessing/python/Impl/trackingOnlyEra_Run3.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _trackingOnlyEra_Run3
 
diff --git a/Configuration/DataProcessing/python/Merge.py b/Configuration/DataProcessing/python/Merge.py
index b34dcb7a197d6..bfebdeecbc3c4 100644
--- a/Configuration/DataProcessing/python/Merge.py
+++ b/Configuration/DataProcessing/python/Merge.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _Merge_
 
diff --git a/Configuration/DataProcessing/python/Reco.py b/Configuration/DataProcessing/python/Reco.py
index 5bb1579a7e989..5a00fae062671 100644
--- a/Configuration/DataProcessing/python/Reco.py
+++ b/Configuration/DataProcessing/python/Reco.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _pp_
 
diff --git a/Configuration/DataProcessing/python/Repack.py b/Configuration/DataProcessing/python/Repack.py
index 399a9d661633f..8b68bc36f8ffe 100644
--- a/Configuration/DataProcessing/python/Repack.py
+++ b/Configuration/DataProcessing/python/Repack.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _Repack_
 
diff --git a/Configuration/DataProcessing/python/Scenario.py b/Configuration/DataProcessing/python/Scenario.py
index 4f828572ba9d8..ad264769c36cc 100644
--- a/Configuration/DataProcessing/python/Scenario.py
+++ b/Configuration/DataProcessing/python/Scenario.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _Scenario_
 
diff --git a/Configuration/DataProcessing/python/Utils.py b/Configuration/DataProcessing/python/Utils.py
index 4a20103ca0aee..fe3d37ad90689 100644
--- a/Configuration/DataProcessing/python/Utils.py
+++ b/Configuration/DataProcessing/python/Utils.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _Utils_
 
diff --git a/Configuration/DataProcessing/test/GetScenario_t.py b/Configuration/DataProcessing/test/GetScenario_t.py
index c8c03f1b05422..0364cb97dcf2b 100644
--- a/Configuration/DataProcessing/test/GetScenario_t.py
+++ b/Configuration/DataProcessing/test/GetScenario_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _GetScenario_
 
diff --git a/Configuration/DataProcessing/test/HeavyIonsEra_Run2_HI_t.py b/Configuration/DataProcessing/test/HeavyIonsEra_Run2_HI_t.py
index 48446d184cc32..12cb70f810318 100644
--- a/Configuration/DataProcessing/test/HeavyIonsEra_Run2_HI_t.py
+++ b/Configuration/DataProcessing/test/HeavyIonsEra_Run2_HI_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _HeavyIonsEra_Run2_HI_
 
diff --git a/Configuration/DataProcessing/test/Monitoring_t.py b/Configuration/DataProcessing/test/Monitoring_t.py
index 4df2cb2a3c4d4..c50ce1f4a378e 100644
--- a/Configuration/DataProcessing/test/Monitoring_t.py
+++ b/Configuration/DataProcessing/test/Monitoring_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # encoding: utf-8
 """
 Monitoring_t.py
diff --git a/Configuration/DataProcessing/test/RunAlcaHarvesting.py b/Configuration/DataProcessing/test/RunAlcaHarvesting.py
index 0dbd19672aaba..10ddfd7529744 100644
--- a/Configuration/DataProcessing/test/RunAlcaHarvesting.py
+++ b/Configuration/DataProcessing/test/RunAlcaHarvesting.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _RunAlcaHarvesting_
 
diff --git a/Configuration/DataProcessing/test/RunAlcaSkimming.py b/Configuration/DataProcessing/test/RunAlcaSkimming.py
index 82257c7007472..15dcb72cb8a11 100644
--- a/Configuration/DataProcessing/test/RunAlcaSkimming.py
+++ b/Configuration/DataProcessing/test/RunAlcaSkimming.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _RunAlcaSkimming_
 
diff --git a/Configuration/DataProcessing/test/RunDQMHarvesting.py b/Configuration/DataProcessing/test/RunDQMHarvesting.py
index 2fffd899b4888..a74f5c6b57621 100644
--- a/Configuration/DataProcessing/test/RunDQMHarvesting.py
+++ b/Configuration/DataProcessing/test/RunDQMHarvesting.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _RunDQMHarvesting_
 
diff --git a/Configuration/DataProcessing/test/RunExpressProcessing.py b/Configuration/DataProcessing/test/RunExpressProcessing.py
index 0728f8eb7d2c4..4540096ff4ac4 100644
--- a/Configuration/DataProcessing/test/RunExpressProcessing.py
+++ b/Configuration/DataProcessing/test/RunExpressProcessing.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _RunExpressProcessing_
 
diff --git a/Configuration/DataProcessing/test/RunMerge.py b/Configuration/DataProcessing/test/RunMerge.py
index a8fca59b84bc0..65ba13e7b4e09 100644
--- a/Configuration/DataProcessing/test/RunMerge.py
+++ b/Configuration/DataProcessing/test/RunMerge.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _RunMerge_
 
diff --git a/Configuration/DataProcessing/test/RunPromptReco.py b/Configuration/DataProcessing/test/RunPromptReco.py
index bf7b5d17aad4f..5a0b7621c38ce 100644
--- a/Configuration/DataProcessing/test/RunPromptReco.py
+++ b/Configuration/DataProcessing/test/RunPromptReco.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _RunPromptReco_
 Test wrapper to generate a reco config and actually push it into cmsRun for
diff --git a/Configuration/DataProcessing/test/RunRepack.py b/Configuration/DataProcessing/test/RunRepack.py
index d8fdda532ced0..2004cea83e88e 100644
--- a/Configuration/DataProcessing/test/RunRepack.py
+++ b/Configuration/DataProcessing/test/RunRepack.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _RunRepack_
 
diff --git a/Configuration/DataProcessing/test/RunVisualizationProcessing.py b/Configuration/DataProcessing/test/RunVisualizationProcessing.py
index 381807163355a..46017dab3721f 100644
--- a/Configuration/DataProcessing/test/RunVisualizationProcessing.py
+++ b/Configuration/DataProcessing/test/RunVisualizationProcessing.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _RunVisualizationProcessing_
 
diff --git a/Configuration/DataProcessing/test/cosmicsEra_Run2_2016_t.py b/Configuration/DataProcessing/test/cosmicsEra_Run2_2016_t.py
index 2851eda4768f4..67edb6e6f25f4 100644
--- a/Configuration/DataProcessing/test/cosmicsEra_Run2_2016_t.py
+++ b/Configuration/DataProcessing/test/cosmicsEra_Run2_2016_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsEra_Run2_2016_
 
diff --git a/Configuration/DataProcessing/test/cosmicsEra_Run2_2017_t.py b/Configuration/DataProcessing/test/cosmicsEra_Run2_2017_t.py
index bdf04f3424dfe..3f73aea0fb11a 100644
--- a/Configuration/DataProcessing/test/cosmicsEra_Run2_2017_t.py
+++ b/Configuration/DataProcessing/test/cosmicsEra_Run2_2017_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsEra_Run2_2017_
 
diff --git a/Configuration/DataProcessing/test/cosmicsEra_Run2_2018_t.py b/Configuration/DataProcessing/test/cosmicsEra_Run2_2018_t.py
index 78cf326b6dc8d..117e6f02d4137 100644
--- a/Configuration/DataProcessing/test/cosmicsEra_Run2_2018_t.py
+++ b/Configuration/DataProcessing/test/cosmicsEra_Run2_2018_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsEra_Run2_2018_
 
diff --git a/Configuration/DataProcessing/test/cosmicsEra_Run3_t.py b/Configuration/DataProcessing/test/cosmicsEra_Run3_t.py
index f3e01439f8643..466abac5ae122 100644
--- a/Configuration/DataProcessing/test/cosmicsEra_Run3_t.py
+++ b/Configuration/DataProcessing/test/cosmicsEra_Run3_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmicsEra_Run3_
 
diff --git a/Configuration/DataProcessing/test/cosmics_t.py b/Configuration/DataProcessing/test/cosmics_t.py
index b1363baf34800..20ef70cd30ad4 100644
--- a/Configuration/DataProcessing/test/cosmics_t.py
+++ b/Configuration/DataProcessing/test/cosmics_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _cosmics_
 
diff --git a/Configuration/DataProcessing/test/ppEra_Run2_2016_t.py b/Configuration/DataProcessing/test/ppEra_Run2_2016_t.py
index 53954412c034b..3f74a629cebad 100644
--- a/Configuration/DataProcessing/test/ppEra_Run2_2016_t.py
+++ b/Configuration/DataProcessing/test/ppEra_Run2_2016_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2016_
 
diff --git a/Configuration/DataProcessing/test/ppEra_Run2_2017_t.py b/Configuration/DataProcessing/test/ppEra_Run2_2017_t.py
index 3e0b9eb7a59bc..a8a6335438954 100644
--- a/Configuration/DataProcessing/test/ppEra_Run2_2017_t.py
+++ b/Configuration/DataProcessing/test/ppEra_Run2_2017_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2017_
 
diff --git a/Configuration/DataProcessing/test/ppEra_Run2_2018_t.py b/Configuration/DataProcessing/test/ppEra_Run2_2018_t.py
index 227f6a69a406e..1825e6a5cc889 100644
--- a/Configuration/DataProcessing/test/ppEra_Run2_2018_t.py
+++ b/Configuration/DataProcessing/test/ppEra_Run2_2018_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_2018_
 
diff --git a/Configuration/DataProcessing/test/ppEra_Run2_50ns_t.py b/Configuration/DataProcessing/test/ppEra_Run2_50ns_t.py
index 1f8a2682fefbe..f540e7fbc1d03 100644
--- a/Configuration/DataProcessing/test/ppEra_Run2_50ns_t.py
+++ b/Configuration/DataProcessing/test/ppEra_Run2_50ns_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run2_50ns_
 
diff --git a/Configuration/DataProcessing/test/ppEra_Run3_t.py b/Configuration/DataProcessing/test/ppEra_Run3_t.py
index bd048a5465a19..5d953f78438ea 100644
--- a/Configuration/DataProcessing/test/ppEra_Run3_t.py
+++ b/Configuration/DataProcessing/test/ppEra_Run3_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _ppEra_Run3_
 
diff --git a/Configuration/DataProcessing/test/pp_reco_t.py b/Configuration/DataProcessing/test/pp_reco_t.py
index 32da8b4117243..045d8d7d46486 100644
--- a/Configuration/DataProcessing/test/pp_reco_t.py
+++ b/Configuration/DataProcessing/test/pp_reco_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _pp_
 
diff --git a/Configuration/DataProcessing/test/pp_t.py b/Configuration/DataProcessing/test/pp_t.py
index 442f2b7290437..e49088bc62ff3 100644
--- a/Configuration/DataProcessing/test/pp_t.py
+++ b/Configuration/DataProcessing/test/pp_t.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 _pp_
 
diff --git a/Configuration/PyReleaseValidation/data/runall.py b/Configuration/PyReleaseValidation/data/runall.py
index 6652c86236eb8..5a94ed3e2e855 100755
--- a/Configuration/PyReleaseValidation/data/runall.py
+++ b/Configuration/PyReleaseValidation/data/runall.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 from __future__ import print_function
 import os
diff --git a/Configuration/PyReleaseValidation/python/MatrixToProcess.py b/Configuration/PyReleaseValidation/python/MatrixToProcess.py
index d09808ca9cd5b..6ed9282085fe2 100644
--- a/Configuration/PyReleaseValidation/python/MatrixToProcess.py
+++ b/Configuration/PyReleaseValidation/python/MatrixToProcess.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 
 from __future__ import print_function
diff --git a/Configuration/PyReleaseValidation/scripts/runTheMatrix.py b/Configuration/PyReleaseValidation/scripts/runTheMatrix.py
index 55d89e6913634..94456a3f63230 100755
--- a/Configuration/PyReleaseValidation/scripts/runTheMatrix.py
+++ b/Configuration/PyReleaseValidation/scripts/runTheMatrix.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 from __future__ import print_function
 import sys, os
 
diff --git a/FWCore/ParameterSet/test/cmsconfig.py b/FWCore/ParameterSet/test/cmsconfig.py
index 8e08e410363c7..d5332c8bdc1a2 100644
--- a/FWCore/ParameterSet/test/cmsconfig.py
+++ b/FWCore/ParameterSet/test/cmsconfig.py
@@ -23,7 +23,7 @@
 # guts without repeating the classname, etc.
 #------------------------------------------------------------
 
-import cStringIO
+import io
 import types
 import six
 
@@ -36,7 +36,7 @@
 def pset_dict_to_string(psetDict):
     """Convert dictionary representing a PSet to a string consistent
     with the configuration grammar."""
-    stream = cStringIO.StringIO()
+    stream = io.StringIO()
     stream.write('\n{\n')
 
     for name, value in six.iteritems(psetDict):
@@ -49,7 +49,7 @@ def pset_dict_to_string(psetDict):
 
 def secsource_dict_to_string(secSourceDict):
     """Make a string representing the secsource"""
-    stream = cStringIO.StringIO()
+    stream = io.StringIO()
     stream.write("%s\n{\n" %  secSourceDict["@classname"][2])
     for name, value in six.iteritems(secSourceDict):
         if name[0] != '@':
@@ -238,7 +238,7 @@ def asConfigurationString(self):
         result = ""
 
         try:
-            stream = cStringIO.StringIO()
+            stream = io.StringIO()
             self.__write_self_to_stream(stream)
             result = stream.getvalue()
 
diff --git a/FWCore/Skeletons/python/cms.py b/FWCore/Skeletons/python/cms.py
index b4852e8b6761a..a324f3cedc909 100644
--- a/FWCore/Skeletons/python/cms.py
+++ b/FWCore/Skeletons/python/cms.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
@@ -44,7 +44,7 @@ def config(tmpl, pkg_help):
     elif len(sys.argv) == 1:
         # need to walk
         msg = 'Please enter %s name: ' % tmpl.lower()
-        kwds['pname'] = raw_input(msg)
+        kwds['pname'] = input(msg)
     else:
         print(pkg_help)
         sys.exit(0)
diff --git a/FWCore/Skeletons/python/main.py b/FWCore/Skeletons/python/main.py
index 296fc75ed7276..e7ebf5462a196 100755
--- a/FWCore/Skeletons/python/main.py
+++ b/FWCore/Skeletons/python/main.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
diff --git a/FWCore/Skeletons/python/pkg.py b/FWCore/Skeletons/python/pkg.py
index 1f04933456797..ce72bdd2fcab9 100644
--- a/FWCore/Skeletons/python/pkg.py
+++ b/FWCore/Skeletons/python/pkg.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=W0122,R0914,R0912
 
diff --git a/FWCore/Skeletons/python/utils.py b/FWCore/Skeletons/python/utils.py
index 04b6b45468f14..6812c7c6c6475 100644
--- a/FWCore/Skeletons/python/utils.py
+++ b/FWCore/Skeletons/python/utils.py
@@ -84,14 +84,14 @@ def functor(code, kwds, debug=0):
             raise Exception(msg)
         args.append(arg)
     func  = '\nimport sys'
-    func += '\nimport StringIO'
+    func += '\nimport io'
     func += "\ndef func(%s):\n" % ','.join(args)
     func += code
     func += """
 def capture():
     "Capture snippet printous"
     old_stdout = sys.stdout
-    sys.stdout = StringIO.StringIO()
+    sys.stdout = io.StringIO()
     func()
     out = sys.stdout.getvalue()
     sys.stdout = old_stdout
diff --git a/FWCore/Skeletons/scripts/mkdatapkg b/FWCore/Skeletons/scripts/mkdatapkg
index 0f2b43f7b9533..6092c06092f32 100755
--- a/FWCore/Skeletons/scripts/mkdatapkg
+++ b/FWCore/Skeletons/scripts/mkdatapkg
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
diff --git a/FWCore/Skeletons/scripts/mkdqmedanalyzer b/FWCore/Skeletons/scripts/mkdqmedanalyzer
index 131028ea2dba8..afb227eb27f65 100755
--- a/FWCore/Skeletons/scripts/mkdqmedanalyzer
+++ b/FWCore/Skeletons/scripts/mkdqmedanalyzer
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
diff --git a/FWCore/Skeletons/scripts/mkedanlzr b/FWCore/Skeletons/scripts/mkedanlzr
index 994fe09aa51d6..ea109a38ad8b0 100755
--- a/FWCore/Skeletons/scripts/mkedanlzr
+++ b/FWCore/Skeletons/scripts/mkedanlzr
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
diff --git a/FWCore/Skeletons/scripts/mkedfltr b/FWCore/Skeletons/scripts/mkedfltr
index 12159f382103f..babdd0a08c47a 100755
--- a/FWCore/Skeletons/scripts/mkedfltr
+++ b/FWCore/Skeletons/scripts/mkedfltr
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
diff --git a/FWCore/Skeletons/scripts/mkedlpr b/FWCore/Skeletons/scripts/mkedlpr
index 0a66ad26edb4f..3a8538c661cca 100755
--- a/FWCore/Skeletons/scripts/mkedlpr
+++ b/FWCore/Skeletons/scripts/mkedlpr
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
@@ -52,7 +52,7 @@ def config(tmpl, pkg_help):
     args  = []
     if  len(sys.argv) >= 2: # user give us arguments
         if  sys.argv[1] in ['-h', '--help', '-help']:
-            print pkg_help
+            print(pkg_help)
             sys.exit(0)
         kwds['pname'] = sys.argv[1]
         for idx in xrange(2, len(sys.argv)):
@@ -63,7 +63,7 @@ def config(tmpl, pkg_help):
                 etags.append('@%s' % opt)
                 continue
             elif  opt in ['-h', '--help', '-help']:
-                print pkg_help
+                print(pkg_help)
                 sys.exit(0)
             elif  opt == '-debug':
                 kwds['debug'] = True
@@ -73,13 +73,13 @@ def config(tmpl, pkg_help):
     elif len(sys.argv) == 1:
         # need to walk
         msg   = 'Please enter %s name: ' % tmpl.lower()
-        kwds['pname'] = raw_input(msg)
+        kwds['pname'] = input(msg)
         msg   = 'Please enter record name: '
-        args.append(raw_input(msg))
+        args.append(input(msg))
         msg   = 'Please enter data types (separate by space): '
-        args += [t for t in raw_input(msg).split()]
+        args += [t for t in input(msg).split()]
     else:
-        print pkg_help
+        print(pkg_help)
         sys.exit(0)
     if  args:
         # first element is record name, others are data types
diff --git a/FWCore/Skeletons/scripts/mkedprod b/FWCore/Skeletons/scripts/mkedprod
index 8260ffffae3f8..1115992785985 100755
--- a/FWCore/Skeletons/scripts/mkedprod
+++ b/FWCore/Skeletons/scripts/mkedprod
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
diff --git a/FWCore/Skeletons/scripts/mkesprod b/FWCore/Skeletons/scripts/mkesprod
index 7a08764fa692c..6290b03d3bff0 100755
--- a/FWCore/Skeletons/scripts/mkesprod
+++ b/FWCore/Skeletons/scripts/mkesprod
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
@@ -55,7 +55,7 @@ def config(tmpl, pkg_help):
     args  = []
     if  len(sys.argv) >= 2: # user give us arguments
         if  sys.argv[1] in ['-h', '--help', '-help']:
-            print pkg_help
+            print(pkg_help)
             sys.exit(0)
         kwds['pname'] = sys.argv[1]
         for idx in xrange(2, len(sys.argv)):
@@ -66,7 +66,7 @@ def config(tmpl, pkg_help):
                 etags.append('@%s' % opt)
                 continue
             elif  opt in ['-h', '--help', '-help']:
-                print pkg_help
+                print(pkg_help)
                 sys.exit(0)
             elif  opt == '-debug':
                 kwds['debug'] = True
@@ -76,13 +76,13 @@ def config(tmpl, pkg_help):
     elif len(sys.argv) == 1:
         # need to walk
         msg   = 'Please enter %s name: ' % tmpl.lower()
-        kwds['pname'] = raw_input(msg)
+        kwds['pname'] = input(msg)
         msg   = 'Please enter record name: '
-        args.append(raw_input(msg))
+        args.append(input(msg))
         msg   = 'Please enter data types (separate by space): '
-        args += [t for t in raw_input(msg).split()]
+        args += [t for t in input(msg).split()]
     else:
-        print pkg_help
+        print(pkg_help)
         sys.exit(0)
     if  args:
         # first element is record name, others are data types
diff --git a/FWCore/Skeletons/scripts/mkrecord b/FWCore/Skeletons/scripts/mkrecord
index cd05b8c35a51f..c786cff0ec1c3 100755
--- a/FWCore/Skeletons/scripts/mkrecord
+++ b/FWCore/Skeletons/scripts/mkrecord
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
diff --git a/FWCore/Skeletons/scripts/mkskel b/FWCore/Skeletons/scripts/mkskel
index 496cda819ff6b..b6e63bbc5838c 100755
--- a/FWCore/Skeletons/scripts/mkskel
+++ b/FWCore/Skeletons/scripts/mkskel
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """
diff --git a/FWCore/Skeletons/scripts/mktmpl b/FWCore/Skeletons/scripts/mktmpl
index 948c2b60d1c13..fb9e78c1f1619 100755
--- a/FWCore/Skeletons/scripts/mktmpl
+++ b/FWCore/Skeletons/scripts/mktmpl
@@ -3,7 +3,7 @@
 cmd=mktmpl
 export MKTMPL_CMD=$cmd
 # find out where Skeleton is installed on a system
-sroot=`python -c "import FWCore.Skeletons; print '/'.join(FWCore.Skeletons.__file__.split('/')[:-1])"`
+sroot=`python3 -c "import FWCore.Skeletons; print('/'.join(FWCore.Skeletons.__file__.split('/')[:-1]))"`
 # run actual script
 tdir=`echo $0 | sed "s,/$cmd,,g"`
 python $sroot/main.py --tdir=$tdir/mkTemplates ${1+"$@"}
diff --git a/FWCore/Skeletons/scripts/mktsel b/FWCore/Skeletons/scripts/mktsel
index f8c6c7c50a071..ef933d6d4bed8 100755
--- a/FWCore/Skeletons/scripts/mktsel
+++ b/FWCore/Skeletons/scripts/mktsel
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #-*- coding: utf-8 -*-
 #pylint: disable-msg=
 """