diff --git a/manifest.toml b/manifest.toml
index 0c6a3b0..c9b947d 100644
--- a/manifest.toml
+++ b/manifest.toml
@@ -7,7 +7,7 @@ name = "Friendica"
 description.en = "Decentralized Social Network"
 description.fr = "Réseau social décentralisé"
 
-version = "2023.12~ynh3"
+version = "2023.12~ynh4"
 
 maintainers = [ "" ]
 
diff --git a/scripts/upgrade b/scripts/upgrade
index 4a1ca5b..5396ec8 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -38,6 +38,11 @@ fi
 chmod -R o-rwx "$install_dir"
 chown -R "$app:www-data" "$install_dir"
 
+# clear the smarty cache
+# cf: https://github.com/friendica/friendica/issues/11212#issuecomment-1046051750
+ynh_secure_remove --file="$install_dir/view/smarty3/compiled"
+chmod -R 775 "$install_dir/view/smarty3"
+
 #=================================================
 # REAPPLY SYSTEM CONFIGURATIONS
 #=================================================