Ticket #45438: 45438.2.patch

src/wp-admin/options.php

@@ -222 +222 @@
                 if ( is_multisite() && ! current_user_can( 'manage_network_options' ) ) {
                         wp_die( __( 'Sorry, you are not allowed to modify unregistered settings for this site.' ) );
                 }
-                $options = explode( ',', wp_unslash( $_POST['page_options'] ) );
+                $options = isset( $_POST['page_options'] ) ? explode( ',', wp_unslash( $_POST[ 'page_options' ] ) ) : null;
         } else {
                 $options = $whitelist_options[ $option_page ];
         }
@@ -293 +293 @@
                 if ( $user_language_old !== $user_language_new ) {
                         load_default_textdomain( $user_language_new );
                 }
+        } else {
+                add_settings_error( 'general', 'settings_updated', __( 'Settings save failed.' ), 'error' );
         }
 
         /**