title: Uncaught TYPO3 Exception: Cannot use object of type __PHP_Incomplete_Class as array
body: <pre><code>Core: Exception handler (WEB): Uncaught TYPO3 Exception: Cannot use object of type __PHP_Incomplete_Class as array | Error thrown in file typo3/sysext/backend/Classes/Controller/Page/TreeController.php in line 189
  </code></pre>
  
  <p>This happened after a core update to TYPO3 - 9.5.17</p>