diff --git a/debian/postinst b/debian/postinst
new file mode 100755
index 0000000..4e4e382
--- /dev/null
+++ b/debian/postinst
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+set -e
+
+PATH=/bin:/sbin:/usr/bin:/usr/sbin
+
+case "$1" in
+    configure)
+          cat <<-END
+
+		======= Important RevPiPyLoad post-installation note =======
+
+		If you upgrade from pre 0.6.5 Version,you have to migrate to the
+		new config file format!!!
+		                            /etc/revpipyload/revpipyload.conf
+
+		READ:
+		      DE: https://revpimodio.org/revpipyplc-auf-065/
+		      EN: https://revpimodio.org/en/revpipyplc-to-064/
+
+	END
+     ;;
+esac
+
+#DEBHELPER#
+
+exit 0
diff --git a/revpipyload/plcsystem.py b/revpipyload/plcsystem.py
index c02e045..8c023d6 100644
--- a/revpipyload/plcsystem.py
+++ b/revpipyload/plcsystem.py
@@ -77,6 +77,8 @@ class RevPiPlc(Thread):
 
     def _setuppopen(self):
         """Setzt UID und GID fuer das PLC Programm."""
+        proginit.logger.debug("enter RevPiPlc._setuppopen()")
+
         proginit.logger.info(
             "set uid {0} and gid {1} for plc program".format(
                 self.uid, self.gid)
@@ -84,6 +86,8 @@ class RevPiPlc(Thread):
         os.setgid(self.gid)
         os.setuid(self.uid)
 
+        proginit.logger.debug("leave RevPiPlc._setuppopen()")
+
     def _spopen(self, lst_proc):
         """Startet das PLC Programm.
         @param lst_proc Prozessliste
@@ -94,7 +98,7 @@ class RevPiPlc(Thread):
             lst_proc,
             preexec_fn=self._setuppopen,
             cwd=os.path.dirname(self._program),
-            bufsize=1,
+            bufsize=0,
             stdout=sysstdout if self._plw is None else self._plw.fdw,
             stderr=subprocess.STDOUT
         )