TYPO3 Core

The sys log gets flooded by those errors when opening a content element that includes the CKEditor (v12.4.8)

Core: Error handler (BE): PHP Warning: file_exists(): open_basedir restriction in effect. File(/_assets/xyz/Css/editor.css) is not within the allowed path(s): (/var/www/vhosts/my-website/:/tmp/) in /var/www/vhosts/my-website/vendor/typo3/cms-core/Classes/Utility/GeneralUtility.php line 2162

The original css file is located in /var/www/vhosts/my-website/vendor/typo3/cms-rte-ckeditor/Resources/Public/Css/editor.css and "_assets/xyz" is the symlink to the CKEditor's public folder.

The file path is returned as part of the array of TYPO3\CMS\RteCKEditor\Form\Element\RichTextElement::render().

$resultArray['stylesheetFiles'][] = PathUtility::getPublicResourceWebPath('EXT:rte_ckeditor/Resources/Public/Css/editor.css');