diff --git a/core/lib/Drupal/Core/Template/TwigExtension.php b/core/lib/Drupal/Core/Template/TwigExtension.php
index 69f3298..ae3adf4 100644
--- a/core/lib/Drupal/Core/Template/TwigExtension.php
+++ b/core/lib/Drupal/Core/Template/TwigExtension.php
@@ -400,6 +400,9 @@ public function escapePlaceholder($env, $string) {
    * @return string|null
    *   The escaped, rendered output, or NULL if there is no valid output.
    *
+   * @throws \Exception
+   *   When passed $string as an object that has no __toString() method.
+   *
    * @todo Refactor this to keep it in sync with theme_render_and_autoescape()
    *   in https://www.drupal.org/node/2575065
    */
@@ -483,6 +486,9 @@ public function escapeFilter(\Twig_Environment $env, $arg, $strategy = 'html', $
    * @return mixed
    *   The rendered output or an Twig_Markup object.
    *
+   * @throws \Exception
+   *   When passed $string as an object that has no __toString() method.
+   *
    * @see render
    * @see TwigNodeVisitor
    */