Breaking: #75829 - Removed handling of pre 6.0 files when importing

See forge#75829

Description

The functionality for importing *.t3d files created from installations lower than TYPO3 CMS 6.0 has been removed.

The following public method has been removed: \TYPO3\CMS\Impexp\Import::fixCharsets().

Impact

Importing files into TYPO3 v8 that were created from a TYPO3 4.x installations will result in unexpected behavior, especially when dealing with files and relations.

Calling the PHP method above will result in a fatal PHP error.

Affected Installations

Any installation using the t3d import functionality for importing files that were created from a TYPO3 instance older than TYPO3 6.0.0.

Migration

It is recommended to import files in a 6.x or 7.x installation and export the files from there again to import them in TYPO3 v8.