diff --git a/scripts/backup b/scripts/backup
index 8a35241..1231263 100755
--- a/scripts/backup
+++ b/scripts/backup
@@ -22,8 +22,14 @@ DESTDIR="/var/www/$app"
 ynh_backup "$DESTDIR" "www"
 
 # Copy the data directory
-DATADIR="/home/yunohost.app/${app}/data"
-ynh_backup "$DATADIR" "data" 1
+backup_core_only=$(ynh_app_setting_get "$app" backup_core_only)
+if [ -z $backup_core_only ]	# Si backup_core_only a une valeur dans le fichier settings.yml, ne sauvegarde pas le dossier data
+then
+	DATADIR="/home/yunohost.app/${app}/data"
+	ynh_backup "$DATADIR" "data" 1
+else
+	echo "Data dir will not saved, because backup_core_only is set." >&2
+fi
 
 # Copy the conf files
 mkdir ./conf
diff --git a/scripts/restore b/scripts/restore
index a88e502..2b285cc 100755
--- a/scripts/restore
+++ b/scripts/restore
@@ -55,7 +55,11 @@ sudo useradd -c "$app system account" \
 # Restore the app files
 sudo cp -a ./www "$DESTDIR"
 sudo mkdir -p "$DATADIR"
-sudo cp -a ./data/. "$DATADIR"
+if [ -d ./data ]	# Le dossier data est restauré seulement si il existe. Si le backup a été fait avec l'option backup_core_only, ce dossier n'a pas été sauvegardé.
+then
+	sudo cp -a ./data/. "$DATADIR"
+fi
+ynh_app_setting_delete $app backup_core_only	# Retire l'option backup_core_only du fichier settings.yml le cas échéant
 
 # Create and restore the database
 ynh_mysql_create_db "$dbname" "$dbuser" "$dbpass"
diff --git a/scripts/upgrade b/scripts/upgrade
index fb84763..031fec5 100755
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -3,6 +3,9 @@
 # Load common variables and helpers
 source ./_common.sh
 
+# Source app helpers
+source /usr/share/yunohost/helpers
+
 # Set app specific variables
 app=$APPNAME
 real_app=$YNH_APP_INSTANCE_NAME	# real_app prendra la valeur nextcloud ou owncloud dans le cas d'une migration
@@ -10,27 +13,40 @@ dbname=$app
 dbuser=$app
 
 # Backup the current version of the app, restore it if the upgrade fails
-if sudo yunohost backup list | grep -q $real_app-before-upgrade > /dev/null 2>&1; then	# Supprime l'ancienne archive seulement si elle existe
-	sudo yunohost backup delete $real_app-before-upgrade
+backup_number=1
+old_backup_number=2
+if sudo yunohost backup list | grep -q $app-before-upgrade1 > /dev/null 2>&1; then	# Vérifie l'existence d'une archive déjà numéroté à 1.
+	backup_number=2	# Et passe le numéro de l'archive à 2
+	old_backup_number=1
 fi
-sudo yunohost backup create --ignore-hooks --apps $real_app --name $real_app-before-upgrade
+ynh_app_setting_set $app backup_core_only 1	# Indique au backup/restore de ne pas sauvegarder le dossier de data, uniquement le core de nextcloud.
+sudo yunohost backup create --ignore-hooks --apps $app --name $app-before-upgrade$backup_number	# Créer un backup différent de celui existant.
+if [ "$?" -eq 0 ]; then	# Si le backup est un succès, supprime l'archive précédente.
+	if sudo yunohost backup list | grep -q $app-before-upgrade$old_backup_number > /dev/null 2>&1; then	# Vérifie l'existence de l'ancienne archive avant de la supprimer, pour éviter une erreur.
+		sudo yunohost backup delete $app-before-upgrade$old_backup_number > /dev/null
+	fi
+else	# Si le backup a échoué
+	ynh_die "Backup failed, the upgrade process was aborted."
+fi
+
 EXIT_PROPERLY () {
 	exit_code=$?
 	if [ "$exit_code" -eq 0 ]; then
+		ynh_app_setting_delete $app backup_core_only
 		exit 0	# Quitte sans erreur si le script se termine correctement.
 	fi
 	trap '' EXIT
 	set +eu
-	sudo yunohost app remove $real_app	# Supprime l'application avant de la restaurer.
-	sudo yunohost backup restore --ignore-hooks $real_app-before-upgrade --apps $real_app --force	# Restore the backup if upgrade failed
-	ynh_die "Upgrade failed. The app was restored to the way it was before the failed upgrade."
+	echo "Upgrade failed." >&2
+	if sudo yunohost backup list | grep -q $app-before-upgrade$backup_number > /dev/null 2>&1; then	# Vérifie l'existence de l'archive avant de supprimer l'application et de restaurer
+		sudo yunohost app remove $app	# Supprime l'application avant de la restaurer.
+		sudo yunohost backup restore --ignore-hooks $app-before-upgrade$backup_number --apps $app --force	# Restore the backup if upgrade failed
+		ynh_die "The app was restored to the way it was before the failed upgrade."
+	fi
 }
 set -eu
 trap EXIT_PROPERLY EXIT
 
-# Source app helpers
-source /usr/share/yunohost/helpers
-
 # Migrate from ownCloud to Nextcloud
 if [[ $YNH_APP_INSTANCE_NAME != $app ]]; then	# Si le nom de l'app donné lors de la commande n'est pas nextcloud, vérifie si c'est owncloud pour lancer la migration.
   [[ $YNH_APP_ID == owncloud ]] \