I'm attempting to replace a node pool in Azure Kubernetes Service with a new pool (that has a larger VM size). The current pool was deployed using an ARM template that uses version 2019-06-01 of the resource manager API. As per the Microsoft documentation I should be able to add a new System node pool and delete the original, default node pool.
I can successfully deploy an additional node pool that has it's mode set to System using this template, that template uses version 2020-03-01 of the resource manager API so that I can set the mode of the new pool.
When I attempt to delete the original, default node pool using
az aks nodepool delete -g gandt-testshared-rg --cluster-name gandt-testshared-aks -n agentpool I get an error saying
Operation failed with status: 'Bad Request'. Details: The agent pool cannot be deleted because it is used as the backend address pool of the basic load balancer..
Why am I getting this error and what can I do to get the backend address pool of the basic load balancer to use the new node pool?
I've deleted the cluster and redeployed using the original ARM template then added the 2nd node pool using az cli command
az aks nodepool add -g gandt-testshared-rg --cluster-name gandt-testshared-aks --name poolb2ms01 --node-count 1 --node-vm-size Standard_B2ms --mode System and got the same result when deleting the default node pool