ons.svg#callout-warning"/></svg></div><div class=content><code>istioctl upgrade</code> is for in-place upgrade and not compatible with installations done with
the <code>--revision</code> flag. Upgrades of such installations will fail with an error.</div></aside></div><h2 id=upgrade-prerequisites>Upgrade prerequisites</h2><p>Before you begin the upgrade process, check the following prerequisites:</p><ul><li><p>The installed Istio version is no more than one minor version less than the upgrade version.
For ex