diff -u b/core/lib/Drupal/Core/Database/Query/Condition.php b/core/lib/Drupal/Core/Database/Query/Condition.php
--- b/core/lib/Drupal/Core/Database/Query/Condition.php
+++ b/core/lib/Drupal/Core/Database/Query/Condition.php
@@ -193,13 +193,7 @@
             // don't rely on a broken SQL statement when we would just replace
             // those characters.
             if (stripos($condition['operator'], 'UNION') !== FALSE || strpbrk($condition['operator'], '[-\'"();') !== FALSE) {
-              $this->changed = TRUE;
-              $this->arguments = [];
-              // Provide a string which will result into an empty query result.
-              $this->stringVersion = '( AND 1 = 0 )';
-
-              trigger_error('Invalid characters in query operator: ' . $condition['operator'], E_USER_ERROR);
-              return;
+              throw new InvalidQueryException('Invalid characters in query operator: ' . $condition['operator']);
             }
             $operator = $connection->mapConditionOperator($condition['operator']);
             if (!isset($operator)) {