referenceindex:update stopped at tt_content with "The Prototype applicationform was not found": the backend and the CLI (form editor, FlexForm of the form plugin, reference index) read module.tx_form, and the form setup was only registered for the frontend (plugin.tx_form). TYPO3 10 set module.tx_form in the site TypoScript; TYPO3 13 reads it only from global TypoScript, so ext_localconf.php registers FormSetup.yaml there. Co-Authored-By: Claude Opus 5.5 <[email protected]>