we want to upgrade AKS from 1.21 to 1.25 as 1.25 is the supported version in AKS right now and AKS does not allow version to upgraded like EKS one minor version at a time.
what are the potential risks?
We have made sure all the deprecated APIs are not used anymore. other than what can be the risks with this big version jump.
The upgrade will be done in the 1.21 cluster not creating a new one. Please let me know in your experience.
As per my experience
After upgrading AKS 1.25.x, we faced High memory consumption issue.
And later when we checked about that issue we got this aks forum link where peoples are discussing about memory issue.
In our case we have to upgrade our NodeJS application to 20.x to match the aks-1.25.x requirement.
And for different applications their are different requirements so you can visit Memory saturation occurs in pods after cluster upgrade to Kubernetes 1.25
As per my suggestion, first of all update your applications so they become compatible with aks 1.25.x