Mark Story goes over a few reasons of why CakePHP 3.0 breaks compatibility in this blog post. Â If you are working with CakePHP or involved in any large system that lives forever, you should read those in detail. Â Otherwise, here is an overview:
- PHP has changed
- Ideas that didn’t work out so well
- Outdated implementations
- Improve consistency
Also, if you are working with CakePHP, you should attend the CakeFest 2014 event next week in Madrid, Spain.