Breaking: #92590 - Removed support for extension upload of t3x files

Description

With the inception of the concept of Extensions, the Extension Manager in TYPO3 and the TYPO3 Extension Repository (TER) on https://extensions.typo3.org, the file format t3x ("TYPO3 eXtension") was created.

The proprietary format was introduced because the lack of support for zip handling in PHP4 in 2004. However, the format was proven to be cumbersome for developers and zip was bundled with most PHP5 versions.

For this reason, the TYPO3 Ecosystem started to support extensions as regular zip archives during TYPO3 v6 development.

The zip format for extension downloading and uploading was used more and more in favor of the t3x data format, so today the TER only offers the download of zip files via the Web GUI.

However, TYPO3's Extension Manager still supported uploading .t3x files even though files were not created by the Extension Manager anymore since TYPO3 v6 - downloading an extension via the Extension Manager only created an archive of the .zip format of the extension.

The feature of uploading files with a t3x format (identified by the file extension .t3x) has been removed.

Both TER and the Extension Manager for downloading extensions still support t3x under the hood for legacy reasons, but this is not exposed to end-users, integrators or developers anymore.

Impact

Uploading a t3x-based extension file in the Extension Manager will result in an error message.

Affected Installations

TYPO3 installations where administrators still handle t3x files for uploading extensions, which is highly unlikely and only applies for TYPO3 installations not installed via Composer.

Migration

When using a public extension, it is recommended to download the zip variant from https://extensions.typo3.org.

When a .t3x file is provided by a third party, it is possible to upload the extension in the Extension Manager of an older TYPO3 Core version (e.g. TYPO3 v10), and then download the extension there as a .zip file.