TYPO3 Core

I discovered the following behaviour in TYPO3 6.2.26. It's possible that this behaviour is also present in later versions.

When having a plugin on a page that has flexform settings and changing this plugin to another one without flexform settings, the pi_flexform field in tt_content is not cleared/invalidated.

Most of the time this has no consequences, but taken the case the first plugin had switchable controller actions leads to the second plugin throwing an exception that the default controller could not be determined because the pi_flexform field is still evaluated even it is a leftover from the first plugin.

This caused 2 hours of debugging for me because the exception siuggested that ext_localconf.php had a typo or something which was not the case. Either the pi_flexform field shuld be emptied when changing a plugin from one to another or the pi_flexform field should only be evaluated if the current plugin actually has flexform settings.