Index: src/wp-admin/includes/update-core.php
===================================================================
--- src/wp-admin/includes/update-core.php	(revision 25860)
+++ src/wp-admin/includes/update-core.php	(working copy)
@@ -728,8 +728,13 @@
 			// Store package-relative paths (the key) of non-writable files in the WP_Error object.
 			$error_data = version_compare( $old_wp_version, '3.7-beta2', '>' ) ? array_keys( $files_not_writable ) : '';
 
-			if ( $files_not_writable )
-				return new WP_Error( 'files_not_writable', __( 'Could not copy file.' ), $error_data );
+			if ( $files_not_writable ) {
+				$files_not_writable_error = new WP_Error( 'files_not_writable', __( 'WordPress cannot write to some files' ), $error_data );
+				if ( defined( 'DOING_CRON' ) && DOING_CRON )
+					return $files_not_writable_error;
+				else
+					show_message( $files_not_writable_error );
+			}
 		}
 	}