diff --git a/cluster/apt.apply.update.sh b/cluster/apt.apply.update.sh
index 55b374b..2baf78d 100755
--- a/cluster/apt.apply.update.sh
+++ b/cluster/apt.apply.update.sh
@@ -66,7 +66,7 @@ debug_message() {                                               # {{{
 
 }
 # }}}
-is_apt_upgrade_absent() {                                                # {{{
+is_apt_upgrade_absent() {                                       # {{{
 
 	## Check if temp APT upgrade file is absent
 	if [ ! -f "${APT_TMP_FILE}" ]; then
@@ -100,7 +100,7 @@ NO APT upgrade available for this system."
 
 }
 # }}}
-is_queue_enable() {                                            # {{{
+is_queue_enable() {                                             # {{{
 
 	local_sge_hostname="${1}"
 	local_sge_queue_name="${2}"
@@ -134,7 +134,7 @@ state is: ${RED}${local_sge_queue_state:=/dev/null}${COLOR_DEBUG}."
 
 }
 # }}}
-is_job_running() {                                            # {{{
+is_job_running() {                                              # {{{
 
 	local_sge_hostname="${1}"
 	## List SGE informations about the host
@@ -164,7 +164,7 @@ jobs running on ${local_sge_hostname} host: ${RED}${local_sge_slots_used}${COLOR
 
 }
 # }}}
-is_proc_running() {                                            # {{{
+is_proc_running() {                                             # {{{
 
 	local_proc_pattern="${1}"
 
@@ -185,6 +185,15 @@ procs running (with the pattern: ${RED}${local_proc_pattern}${COLOR_DEBUG}) on t
 
 	return "${return_proc_running}"
 
+}
+# }}}
+upgrade_system() {                                              # {{{
+
+	debug_message "upgrade_system − \
+Try to apply APT upgrades".
+
+	DEBIAN_FRONTEND=noninteractive aptitude -y -o Dpkg::Options::=--force-confdef -o Dpkg::Options::=--force-confold full-upgrade >> "${APT_TMP_FILE}" 2>&1
+
 }
 # }}}
 main() {                                                        # {{{
@@ -218,9 +227,12 @@ main() {                                                        # {{{
 	is_proc_running "${maco_proc_pattern}" \
 		&& exit 0
 
+	## Try to upgrade the system
+	upgrade_system
+
 }
 # }}}
 
 main
 
-exit 0
+exit 255