This page doesn't document all changes in 2.4, but specifically documents breaking changes that may effect developers migrating to v2.4

Full list of changes since 2.3.2 https://github.com/ushahidi/Ushahidi_Web/compare/2.3.2...master

What's changed

category::tree($categories, $selected_categories, 'incident_category', $columns);

to

category::tree($categories, TRUE, $selected_categories, 'incident_category', $columns);

* Session driver changed to 'database' by default