Ticket #27992: 27992.diff

src/wp-includes/class-wp-customize-manager.php

@@ -394 +394 @@
                 $this->prepare_controls();
 
                 wp_enqueue_script( 'customize-preview' );
+                add_action( 'wp', array( $this, 'customize_preview_override_404_status' ) );
                 add_action( 'wp_head', array( $this, 'customize_preview_base' ) );
                 add_action( 'wp_head', array( $this, 'customize_preview_html5' ) );
                 add_action( 'wp_footer', array( $this, 'customize_preview_settings' ), 20 );
@@ -416 +417 @@
         }
 
         /**
+         * Prevent sending a 404 status when returning the response for the customize
+         * preview, since it causes the jQuery Ajax to fail. Send 200 instead.
+         *
+         * @since 4.0.0
+         */
+        public function customize_preview_override_404_status() {
+                if ( is_404() ) {
+                        status_header( 200 );
+                }
+        }
+
+        /**
          * Print base element for preview frame.
          *
          * @since 3.4.0