diff --git a/src/wp-admin/includes/class-automatic-upgrader-skin.php b/src/wp-admin/includes/class-automatic-upgrader-skin.php
index 4fee6205fc..952b5cd491 100644
--- a/src/wp-admin/includes/class-automatic-upgrader-skin.php
+++ b/src/wp-admin/includes/class-automatic-upgrader-skin.php
@@ -72,6 +72,8 @@ class Automatic_Upgrader_Skin extends WP_Upgrader_Skin {
 	 * @param mixed                 ...$args  Optional text replacements.
 	 */
 	public function feedback( $feedback, ...$args ) {
+		$string = '';
+
 		if ( is_wp_error( $feedback ) ) {
 			$string = $feedback->get_error_message();
 		} elseif ( is_array( $feedback ) ) {