[Retirement] The enableCustomCATrust preview property retires on 14 September 2026.

On 14 September 2026, the preview property `enableCustomCATrust` will retire. After that date, `enableCustomCATrust=true` node pool level field will no longer enable the Custom Certificate Authority (CA) feature in AKS.

The last preview API that supports this property is 2025-08-02-preview.

Existing node pools that still rely on enableCustomCATrust=true might experience failures during scaling operations or when certificates are updated.

### Required Action
To avoid service disruption, update the impacted clusters and node pools and remove the preview property before 14 September 2026.

**Update your node pools to remove the Custom CA Trust property:**

az aks nodepool update \
  --resource-group \
  --cluster-name \
  --name \
  --disable-custom-ca-trust

**Update your clusters to remove the Custom CA Trust property:**
az aks update \
  --resource-group \
  --name \
  --disable-custom-ca-trust

If you want Custom CA Trust enabled on your clusters after this retirement, use --custom-ca-trust-certificates and provide a path to a certificate file. For more information, see [AKS Custom Certificate Authority documentation](https://learn.microsoft.com/azure/aks/custom-certificate-authority).