diff -u b/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
--- b/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -679,7 +679,7 @@
  * always fatal: the execution of the script will stop as soon as the exception
  * handler exits.
  *
- * @param \Exception|\Error $exception
+ * @param \ThrowableInterface $exception
  *   The exception object that was thrown.
  */
 function _drupal_exception_handler($exception) {
@@ -690,11 +690,11 @@
     _drupal_log_error(Error::decodeException($exception), TRUE);
   }
   // PHP 7 introduces Error throwables.
-  catch (Error $exception2) {
-    _drupal_exception_handler_additional($exception, $exception2);
+  catch (\Error $error) {
+    _drupal_exception_handler_additional($exception, $error);
   }
   // In order to be compatibile with PHP 5 we also catch regular Exceptions.
-  catch (Exception $exception2) {
+  catch (\Exception $exception2) {
     _drupal_exception_handler_additional($exception, $exception2);
   }
 }
@@ -702,9 +702,9 @@
 /**
  * Displays any additional errors caught while handling an exception.
  *
- * @param \Exception|\Error $exception
+ * @param \ThrowableInterface $exception
  *   The first exception object that was thrown.
- * @param \Exception|\Error $exception
+ * @param \ThrowableInterface $error
  *   The second exception object that was thrown.
  */
 function _drupal_exception_handler_additional($exception, $exception2) {
@@ -1099,11 +1099,11 @@
     }
   }
   // PHP 7 introduces Error throwables.
-  catch (Error $exception) {
-    _drupal_shutdown_function_handle_exception($exception);
+  catch (\Error $error) {
+    _drupal_shutdown_function_handle_exception($error);
   }
   // In order to be compatibile with PHP 5 we also catch regular Exceptions.
-  catch (Exception $exception) {
+  catch (\Exception $exception) {
     _drupal_shutdown_function_handle_exception($exception);
   }
 }
@@ -1111,7 +1111,7 @@
 /**
  * Displays and logs any errors that may happen during shutdown.
  *
- * @param \Exception|\Error $exception
+ * @param \ThrowableInterface $exception
  *   The exception object that was thrown.
  *
  * @see _drupal_shutdown_function()
diff -u b/core/lib/Drupal/Core/Utility/Error.php b/core/lib/Drupal/Core/Utility/Error.php
--- b/core/lib/Drupal/Core/Utility/Error.php
+++ b/core/lib/Drupal/Core/Utility/Error.php
@@ -33,7 +33,7 @@
   /**
    * Decodes an exception and retrieves the correct caller.
    *
-   * @param \Exception|\Error $exception
+   * @param \ThrowableInterface $exception
    *   The exception object that was thrown.
    *
    * @return array
@@ -82,7 +82,7 @@
   /**
    * Renders an exception error message without further exceptions.
    *
-   * @param \Exception|\Error $exception
+   * @param \ThrowableInterface $exception
    *   The exception object that was thrown.
    *
    * @return string