Upgrade ECK cluster 7.5.2 to 7.6.0

[operatorequals]

Hello people!

A week ago, I used:

kubectl apply -f https://download.elastic.co/downloads/eck/1.0.0/all-in-one.yaml

and created an ES cluster in a Kubernetes (deployed in EC2 instances), of version 7.5.2.

Today, as I wanted to upgrade to the 7.6.0 version, I changed the yaml of the Cluster:

apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
  name: elastic
spec:
  version: 7.6.0 # <-- Here
  updateStrategy:
    changeBudget:
      maxSurge: -1
      maxUnavailable: 0

---

Now I get the following:

$ k get elasticsearches.elasticsearch.k8s.elastic.co 
NAME      HEALTH   NODES   VERSION   PHASE   AGE
elastic   green    3       7.6.0             6d

But the Service itself responds with:

{
  "name" : "elastic-es-default-1",
  "cluster_name" : "elastic",
  "cluster_uuid" : "[...]",
  "version" : {
    "number" : "7.5.2",

Is there something that I am missing?

P.S The error seems the following:

kubectl describe elasticsearches.elasticsearch.k8s.elastic.co 
  Version:                   7.6.0
Status:
  Available Nodes:  3
  Health:           green
Events:
  Type     Reason               Age                  From                      Message
  ----     ------               ----                 ----                      -------
  Warning  ReconciliationError  5s (x647 over 6d2h)  elasticsearch-controller  Failed to apply spec change: StatefulSet.apps "elastic-es-default" is invalid: spec: Forbidden: updates to statefulset spec for fields other than 'replicas', 'template', and 'updateStrategy' are forbidden