Index: src/wp-includes/class-wp-error.php
===================================================================
--- src/wp-includes/class-wp-error.php	(revision 28969)
+++ src/wp-includes/class-wp-error.php	(working copy)
@@ -63,6 +63,15 @@
 
 		if ( ! empty($data) )
 			$this->error_data[$code] = $data;
+
+		/**
+		 * Fires when a WP_Error object instance is created.
+		 *
+		 * @since 4.0.0
+		 *
+		 * @param WP_Error $this The WP_Error instance.
+		 */
+		do_action( 'create_wp_error', $this );
 	}
 
 	/**