From the doc,
The shortcut http://localhost:8001/ui is deprecated. Use the full proxy URL http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/
why ?
API server should only act as an API and it should not provide endpoints that are dependant on external applications being installed inside the cluster. Dashboard is not a built-in application. It is an external UI for kubernetes that might or might not be installed.
Most helpful comment
API server should only act as an API and it should not provide endpoints that are dependant on external applications being installed inside the cluster. Dashboard is not a built-in application. It is an external UI for kubernetes that might or might not be installed.