TYPO3 v8 has reached its end-of-life March 31st, 2020 and is not maintained by the community anymore.
You can order Extended Long Term Support (ELTS) here: TYPO3 ELTS.
Verifying the $TCA¶
You may find it necessary – at some point – to verify the full
structure of the
$GLOBALS['TCA'] in your TYPO3 installation. The System >
Configuration module makes it possible to have an overview of the
$GLOBALS['TCA'], with all customizations taken into account.
If you cannot find your new field, it probably means that you have made some mistake.
This view is also useful when trying to find out where to insert a new field, to explore the combination of types and palettes that may be used for the table that we want to extend.