Breaking: #101392 - getIdentifier() and setIdentifier() from AbstractFile removed 

See forge#101392

Description 

When using the PHP API of the File Abstraction Layer (FAL), several classes are involved in representing file objects.

In addition to the FileInterface , there is also the AbstractFile class, from which most file- related classes inherit.

To ensure stricter type consistency, the abstract class no longer implements the methods getIdentifier() and setIdentifier(). Implementing these methods is now the responsibility of each subclass.

The methods are now implemented in the respective concrete classes inheriting from AbstractFile .

Impact 

In the unlikely case that the TYPO3 File Abstraction Layer has been extended with custom PHP classes derived from AbstractFile , this change will cause a fatal PHP error, as the new abstract methods getIdentifier() and setIdentifier() must be implemented by the subclass.

Affected installations 

TYPO3 installations that include custom code extending the File Abstraction Layer are affected. Such cases are considered highly uncommon.

Migration 

Implement the two methods getIdentifier() and setIdentifier() in any custom file class extending AbstractFile .

This can also be implemented in older TYPO3 versions to ensure forward compatibility with TYPO3 v14 and later.