Joomla\CMS\Cache\Storage\FileStorage::_deleteFolder You can't delete a base folder.
Joomla\CMS\Cache\Storage\FileStorage::_deleteFolder JFolder: :delete: Could not delete folder. Path: [ROOT]/cache/com_k2_extended
Joomla\CMS\Cache\Storage\FileStorage::_deleteFolder Failed deleting index.html
Joomla\CMS\Cache\Storage\FileStorage::_deleteFolder Failed deleting 6a633a0c98ea5db608e68e7375f2b86d-cache-com_k2_extended-c8be8c28f6c30a939b7b206c5064c649.php