Breaking: #102600 - TSFE->applicationData removed

See forge#102600


Frontend-related property TypoScriptFrontendController->applicationData has been removed without substitution.

This property has been used by a few rather old-school extensions to park and communicate state using this global "extension-specific state array".

When looking at the TYPO3 frontend rendering chain, class TypoScriptFrontendController is by far the biggest technical debt: It mixes a lot of concerns and carries tons of state and functionality that should be modeled differently, which leads to easier to understand and more flexible code. The class is shrinking since various major versions already and will ultimately dissolve entirely at some point. Changes in this area are becoming more aggressive with TYPO3 v13. Any code using the class will need adaptions at some point, single patches will continue to communicate alternatives.

In case of the applicationData property, this is simply a misuse of the class instance to park arbitrary state in a global object. This is why it needs to fall and why there is no direct substitution.


Using TypoScriptFrontendController->applicationData (or $GLOBALS['TSFE']->applicationData) will raise a PHP fatal error.

Affected installations

Instances with extensions that use applicationData to store and communicate state.


There are various solutions to communicate state to avoid applicationData:

In some cases, an extension could establish a frontend middleware and attach a request attribute that carries the state.

In other cases an event could be fired to gather information from other extensions. One example is the indexed_search extension which dispatches the new event EnableIndexingEvent to get know if indexing should be performed. The third-party crawler extension should use this instead of setting that information on $GLOBALS['TSFE'].