- Chg: Use `limit(null)` instead of `limit(-1)` in migration controller to be compatible to more backends (cebe)
- Chg: `yii\web\Request::cookieValidationKey` must be explicitly specified for each application that wants to use cookie validation (qiangxue)
- Chg: Added `yii\composer\Installer::postCreateProject()` and modified the syntax of calling installer methods in composer.json (qiangxue)
- Chg: When an ID is found to be in both `Application::controllerMap` and `Application::modules`, the former will take precedence (qiangxue)
- New #3911: Added `yii\behaviors\SluggableBehavior` that fills the specified model attribute with the transliterated and adjusted version to use in URLs (creocoder)
- New #4193: Added `yii\filters\Cors` CORS filter to allow Cross Origin Resource Sharing (pgaultier)