<p>When I try to edit the PVC, Kubernetes gives error saying:</p>

<blockquote>
  <p>The StatefulSet "es-data" is invalid: spec: Forbidden: updates to
  statefulset spec for fields other than 'replicas', 'template', and
  'updateStrategy' are forbidden.</p>
</blockquote>

<p>I am trying to increase the disk size of elasticsearch which is deployed as a statefulset on AKS.</p>

<p>The error is self explaining. You can only update <code>template</code> and <code>updateStrategy</code> part of a StatefulSet. Also, you can't resize a PVC. However, from kubernetes 1.11 you can resize pvc but it is still alpha feature.</p>

<p>Ref: <a href="https://kubernetes.io/docs/concepts/storage/persistent-volumes/#resizing-an-in-use-persistentvolumeclaim" rel="nofollow noreferrer">Resizing an in-use PersistentVolumeClaim</a></p>

<blockquote>
  <p>Note: Alpha features are not enabled by default and you have to enable manually while creating the cluster.</p>
</blockquote>
