.. include:: /Includes.rst.txt

==========================
TYPO3 Exception 1397836158
==========================

.. include:: /If-you-encounter-this-exception.rst.txt

No or invalid extension key "..." given.
========================================

-  Search for variable `$extensionKey` and replace with the extension key as
   `$_EXTKEY` or string `myExtension`
-  Try not to use `$_EXTKEY` in dynamicConfigFiles or otherwise included
   TCA snippets
-  Check https://forge.typo3.org/issues/59033

You may have to clear the cache in install tool (See :guilabel:`Important actions`).

https://docs.typo3.org/typo3cms/InstallationGuide/Upgrade/RemoveTemporaryCacheFiles/Index.html