.</p><p>While beneficial on the long term, each behavioral change introduces risk during upgrades.
Historically, when upgrading users should read the release notes for any behavioral changes and determine if they are impacted; this can be tedious and error prone.</p><p>Compatibility versions give users an additional option, allowing release versions to be decoupled from behavioral changes.
For instance, you can install Istio 1.21, but configure it to behave like 1.20.</p><h2 id=using-compatibility-versions>