Index: wp-includes/rest-api/class-wp-rest-server.php
===================================================================
--- wp-includes/rest-api/class-wp-rest-server.php	(revision 37961)
+++ wp-includes/rest-api/class-wp-rest-server.php	(working copy)
@@ -879,7 +879,7 @@
 						if ( is_wp_error( $permission ) ) {
 							$response = $permission;
 						} else if ( false === $permission || null === $permission ) {
-							$response = new WP_Error( 'rest_forbidden', __( "You don't have permission to do this." ), array( 'status' => 403 ) );
+							$response = new WP_Error( 'rest_forbidden', __( 'Sorry, you are not allowed to do that.' ), array( 'status' => 403 ) );
 						}
 					}
 				}