Upgrading from 4.2.0 to 4.2.1

Please refer to the upgrade instructions corresponding to your installation method.

Mandatory File Changes


  • The mapping of file extensions to MIME types in app/Config/Mimes.php was updated to fix a bug. Also, the logic of Mimes::getExtensionFromType() was changed.

Breaking Changes

Breaking Enhancements

Project Files

Numerous files in the project space (root, app, public, writable) received updates. Due to these files being outside of the system scope they will not be changed without your intervention. There are some third-party CodeIgniter modules available to assist with merging changes to the project space: Explore on Packagist.


Except in very rare cases for bug fixes, no changes made to files for the project space will break your application. All changes noted here are optional until the next major version, and any mandatory changes will be covered in the sections above.

Content Changes

All Changes

This is a list of all files in the project space that received changes; many will be simple comments or formatting that have no effect on the runtime:

  • app/Config/Mimes.php