Breaking: #105855 - Remove file backwards compatibility for alt and link field 

Description 

When the File Abstraction Layer (FAL) was introduced, the TYPO3 Core file fields media for table pages, and image and assets for table tt_content, had their so-called "overlay palettes" overridden to imageOverlayPalette, so that additional fields like alternative, link, and crop were displayed. However, this was done for all file types, including text, application, and the fallback type unknown. For these types, the additional fields served no meaningful purpose. For this reason, they have now been removed.

Impact 

The TYPO3 Core file fields media for table pages, image and assets for table tt_content, will no longer display the fields alternative and link for file types other than image.

Affected installations 

This affects installations that use one of the Core fields for file types other than image (for example text or application) and make use of the fields alternative and/or link.

This should not affect many installations, as these fields are used primarily for images.

Migration 

These fields can be restored using TCA overrides if necessary. First, register a new palette for the sys_file_reference table containing the desired set of fields.

$GLOBALS['TCA']['sys_file_reference']['palettes']['myCustomPalette'] = [
    'label' => 'My custom palette',
    'showitem' => 'alternative,description,--linebreak--,link,title',
];

Then, use this palette for your specific Core field and file type. The following example restores the fields alternative and link for the media field of the pages table when the file type is text.

use TYPO3\CMS\Core\Resource\FileType;

$GLOBALS['TCA']['pages']['columns']['media']['config']['overrideChildTca']
    ['types'][FileType::TEXT->value]['showitem'] =
    '--palette--;;myCustomPalette,--palette--;;filePalette';