diff --git a/src/wp-admin/includes/export.php b/src/wp-admin/includes/export.php
index 9d5903a98c5c3..031d4123025fa 100644
--- a/src/wp-admin/includes/export.php
+++ b/src/wp-admin/includes/export.php
@@ -243,6 +243,10 @@ function export_wp( $args = array() ) {
 	 * @return string
 	 */
 	function wxr_cdata( $str ) {
+		if ( ! is_string( $str ) ) {
+			return '';
+		}
+
 		if ( ! wp_is_valid_utf8( $str ) ) {
 			$str = utf8_encode( $str );
 		}