I've upgraded my AKS nodes in Cluster last night.
After upgraded both nodes, all my apps went down and all my internal load balancers was not able to access.
Spending many hours in troubleshooting and ends up with the miserable findings of root caused.
The Resource Tagging used in my Cluster and it's resource has exceed more than 50 tags.
Microsoft recommendation is to maintain the tags less than 20.
After I've removed over 30 tags and refresh the nodes then only all my resources are back up online as well as the applications.
Currently, the resource sync the tags with cluster are below,
AKS Cluster itself
Network Security Group
AKS managed kubelet msi
AKS managed addon msi
Private DNS zone
So, beware this when you have more than 50 tags on your AKS Cluster.
Have a good day.
(Be knowledgeable, pass it on then)