diff --git a/releases/HEAD/release-ilcsoft.cfg b/releases/HEAD/release-ilcsoft.cfg
index d6113d5c..a2a3e494 100644
--- a/releases/HEAD/release-ilcsoft.cfg
+++ b/releases/HEAD/release-ilcsoft.cfg
@@ -26,7 +26,7 @@ path_where_this_file_lives = os.path.dirname( config_file )
 versions_file = os.path.join( path_where_this_file_lives, "release-versions-HEAD.py" )
 exec(compile(open(versions_file, "rb").read(), versions_file, "exec"))
 
-print "Do we install nightlies? ", nightlies
+print("Do we install nightlies? ", nightlies)
 
 # installation directory
 if not 'ilcsoft_install_dir' in dir():
@@ -75,8 +75,8 @@ ilcsoft.envcmake["Boost_NO_BOOST_CMAKE"] = 'ON'
 ilcsoft.envcmake["INSTALL_DOC"]="OFF"
 
 
-ilcsoft.envcmake["CMAKE_BUILD_TYPE"]= "Debug"
-#ilcsoft.envcmake["CMAKE_BUILD_TYPE"]= "RelWithDebInfo"
+# ilcsoft.envcmake["CMAKE_BUILD_TYPE"]= "Debug"
+ilcsoft.envcmake["CMAKE_BUILD_TYPE"]= "RelWithDebInfo"
 ilcsoft.downloadType = "GitHub"
 #ilcsoft.downloadType = "svn-desy"
 
diff --git a/releases/HEAD/release-versions-HEAD.py b/releases/HEAD/release-versions-HEAD.py
index e2f228fd..4be9d692 100644
--- a/releases/HEAD/release-versions-HEAD.py
+++ b/releases/HEAD/release-versions-HEAD.py
@@ -13,14 +13,6 @@
 ilcsoft_release='HEAD-'+today
 # ----------------------------------------------------------------------------
 
-#-----------------------
-# we now always build with c++11 ?
-# This variable is deprecated and replaced by cxx_standard
-# use_cpp11 = False
-# if nightlies:
-#    use_cpp11 = nb_use_cpp11
-#    print "******************* use_cpp11", use_cpp11
-
 # which cxx standard to use
 cxx_standard = 17
 
@@ -31,18 +23,21 @@
     pass
 
 #===============================================================================
-# use a compiler that knows c++11, run
+# use a compiler that knows c++17, run
 #
 '''
- source /afs/cern.ch/sw/lcg/contrib/gcc/4.9.3/x86_64-slc6/setup.sh
- export PATH=/afs/cern.ch/sw/lcg/releases/LCG_87/Python/2.7.10/x86_64-slc6-gcc49-opt/bin:$PATH
- export LD_LIBRARY_PATH=/afs/cern.ch/sw/lcg/releases/LCG_87/Python/2.7.10/x86_64-slc6-gcc49-opt/lib:$LD_LIBRARY_PATH
+# --- gcc from LCG_99
+source /cvmfs/sft.cern.ch/lcg/releases/gcc/10.1.0/x86_64-centos7/setup.sh
+
+# --- python from LCG_99
+export PATH=/cvmfs/sft.cern.ch/lcg/releases/Python/3.8.6-3199b/x86_64-centos7-gcc10-opt/bin:${PATH}
+export LD_LIBRARY_PATH=/cvmfs/sft.cern.ch/lcg/releases/Python/3.8.6-3199b/x86_64-centos7-gcc10-opt/lib:${LD_LIBRARY_PATH}
 
-# or on cvmfs:
+# --- git from LCG_99
+export PATH=/cvmfs/sft.cern.ch/lcg/releases/git/2.29.2-e475b/x86_64-centos7-gcc10-opt/bin:${PATH}
 
- source /cvmfs/sft.cern.ch/lcg/contrib/gcc/4.9.3/x86_64-slc6/setup.sh
- export PATH=/cvmfs/sft.cern.ch/lcg/releases/LCG_87/Python/2.7.10/x86_64-slc6-gcc49-opt/bin:$PATH
- export LD_LIBRARY_PATH=/cvmfs/sft.cern.ch/lcg/releases/LCG_87/Python/2.7.10/x86_64-slc6-gcc49-opt/lib:$LD_LIBRARY_PATH
+# --- use a suitable mysql (also LCG_99)
+export MYSQL_DIR=/cvmfs/sft.cern.ch/lcg/releases/mysql/10.4.12-8f05c/x86_64-centos7-gcc10-opt
 '''
 # before starting the installation
 #================================================================================
@@ -112,7 +107,7 @@
    platfDefault = '/usr/local'
 
 # ----- mysql --------------------------------------------------------
-MySQL_version = "5.0.45"
+MySQL_version = "5.7.26"
 MySQL_path = platfDefault
 
 # overwrite with a patch set in the environment
diff --git a/scripts/use_gcc101_cvmfs_centos7.sh b/scripts/use_gcc101_cvmfs_centos7.sh
new file mode 100644
index 00000000..aece358f
--- /dev/null
+++ b/scripts/use_gcc101_cvmfs_centos7.sh
@@ -0,0 +1,14 @@
+# --- gcc from LCG_99
+source /cvmfs/sft.cern.ch/lcg/releases/gcc/10.1.0/x86_64-centos7/setup.sh
+
+# --- python from LCG_99
+export PATH=/cvmfs/sft.cern.ch/lcg/releases/Python/3.8.6-3199b/x86_64-centos7-gcc10-opt/bin:${PATH}
+export LD_LIBRARY_PATH=/cvmfs/sft.cern.ch/lcg/releases/Python/3.8.6-3199b/x86_64-centos7-gcc10-opt/lib:${LD_LIBRARY_PATH}
+export PYTHONPATH=/cvmfs/sft.cern.ch/lcg/views/LCG_99/x86_64-centos7-gcc10-opt/lib/python3.8/site-packages
+
+# --- git from LCG_99
+export PATH=/cvmfs/sft.cern.ch/lcg/releases/git/2.29.2-e475b/x86_64-centos7-gcc10-opt/bin:${PATH}
+export GIT_EXEC_PATH=/cvmfs/sft.cern.ch/lcg/releases/git/2.29.2-e475b/x86_64-centos7-gcc10-opt/libexec/git-core
+
+# --- use a suitable mysql (also LCG_99)
+export MYSQL_DIR=/cvmfs/sft.cern.ch/lcg/releases/mysql/10.4.12-8f05c/x86_64-centos7-gcc10-opt