# Upgrading Instructions for Yii Cache

This file contains the upgrade notes. These notes highlight changes that could break your
application when you upgrade the package from one version to another.

> **Important!** The following upgrading instructions are cumulative. That is, if you want
> to upgrade from version A to version C and there is version B between A and C, you need
> to following the instructions for both A and B.

## Upgrade from 3.x

- Change method `normalize()` to static in `CacheKeyNormalizer` class.