diff --git a/scripts/upgrade b/scripts/upgrade
index 1441abb..4db9598 100755
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -10,6 +10,11 @@ upgrade_type=$(ynh_check_app_version_changed)
 #=================================================
 ynh_script_progression --message="Ensuring downward compatibility..."
 
+if [ -z ${system_addressbook_exposed:-} ]; then
+	ynh_app_setting_set --app=$app --key=system_addressbook_exposed --value=0
+    system_addressbook_exposed=0
+fi
+
 # Fix system_addressbook_exposed as a boolean
 if [ "${system_addressbook_exposed,,}" = "yes" ]; then
 	ynh_app_setting_set --app=$app --key=system_addressbook_exposed --value=1
@@ -288,6 +293,12 @@ then
     #=================================================
 
     exec_occ config:system:set overwrite.cli.url --value="https://${domain}${path}"
+    
+    #=================================================
+    # ENABLE OR DISABLE SYSTEM ADDRESS BOOK
+    #=================================================
+
+    exec_occ config:app:set dav system_addressbook_exposed --value="$system_addressbook_exposed"
 
     #=================================================
     # MOUNT HOME FOLDERS AS EXTERNAL STORAGE