diff -u b/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
--- b/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -689,8 +689,9 @@
     // Log the message to the watchdog and return an error page to the user.
     _drupal_log_error(Error::decodeException($exception), TRUE);
   }
-  // PHP 7 introduces Error throwables.
-  catch (\Error $error) {
+  // PHP 7 introduces ThrowableInterface, which covers both Error and
+  // Exception throwables.
+  catch (\ThrowableInterface $error) {
     _drupal_exception_handler_additional($exception, $error);
   }
   // In order to be compatibile with PHP 5 we also catch regular Exceptions.
@@ -1098,8 +1099,9 @@
       call_user_func_array($callback['callback'], $callback['arguments']);
     }
   }
-  // PHP 7 introduces Error throwables.
-  catch (\Error $error) {
+  // PHP 7 introduces ThrowableInterface, which covers both Error and
+  // Exception throwables.
+  catch (\ThrowableInterface $error) {
     _drupal_shutdown_function_handle_exception($error);
   }
   // In order to be compatibile with PHP 5 we also catch regular Exceptions.