api server is responding, as I was able to execute kubectl version right after that error...
per your reply:
kubectl get pods --all-namespaces=true:
$ kubectl get pods --all-namespaces=true
NAMESPACE NAME READY STATUS RESTARTS AGE
elastic-system elastic-operator-0 1/1 Running 0 16m
gitlab-managed-apps certmanager-cert-manager-6df979599b-xltdm 1/1 Running 0 16m
gitlab-managed-apps ingress-nginx-ingress-controller-7cf6944677-5ntrp 1/1 Running 0 16m
gitlab-managed-apps ingress-nginx-ingress-default-backend-7f7bf55777-l744w 1/1 Running 0 16m
gitlab-managed-apps prometheus-kube-state-metrics-5d5958bc-2w2tm 1/1 Running 0 16m
gitlab-managed-apps prometheus-prometheus-server-5c476cc89-qscgj 2/2 Running 0 16m
gitlab-managed-apps runner-gitlab-runner-6947cc549f-fzjr2 1/1 Running 0 16m
gitlab-managed-apps tiller-deploy-7cbfdc5df7-9gxkx 1/1 Running 0 16m
kube-system calico-node-vertical-autoscaler-579467d76c-khp7m 1/1 Running 2 16m
kube-system calico-node-x6cpr 2/2 Running 0 20h
kube-system calico-node-xvdjd 2/2 Running 0 16m
kube-system calico-typha-65bfd5544b-hkcjg 1/1 Running 0 16m
kube-system calico-typha-horizontal-autoscaler-847fc7bc8d-ff7j4 1/1 Running 0 16m
kube-system calico-typha-vertical-autoscaler-dc95cc498-t2qcr 1/1 Running 1 16m
kube-system event-exporter-v0.2.4-5f88c66fb7-gtvpl 2/2 Running 2 16m
kube-system fluentd-gcp-scaler-59b7b75cd7-rtvnr 1/1 Running 0 16m
kube-system fluentd-gcp-v3.2.0-drrg9 2/2 Running 0 16m
kube-system fluentd-gcp-v3.2.0-lvtl6 2/2 Running 0 20h
kube-system heapster-v1.6.0-beta.1-8b5666cf6-57bgr 3/3 Running 2 16m
kube-system ip-masq-agent-2l4fk 1/1 Running 0 16m
kube-system ip-masq-agent-rxw9z 1/1 Running 0 20h
kube-system kube-dns-6987857fdb-457gz 4/4 Running 0 16m
kube-system kube-dns-6987857fdb-tlqw2 4/4 Running 0 20h
kube-system kube-dns-autoscaler-bb58c6784-7p2cn 1/1 Running 0 16m
kube-system kube-proxy-gke-test-default-pool-cbc7ebb8-0z9l 1/1 Running 0 16m
kube-system kube-proxy-gke-test-default-pool-cbc7ebb8-9c5t 1/1 Running 0 20h
kube-system l7-default-backend-fd59995cd-7s4t9 1/1 Running 0 16m
kube-system metrics-server-v0.3.1-57c75779f-mcwgc 2/2 Running 0 16m
kube-system prometheus-to-sd-fxr52 1/1 Running 0 16m
kube-system prometheus-to-sd-tnw7h 1/1 Running 0 20h
kube-system tiller-deploy-58c844889c-2xtcg 1/1 Running 0 16m
$
elastic-operator:
$ kubectl -n elastic-system logs statefulset.apps/elastic-operator | tail -18
{"level":"info","ts":1565407823.1509497,"logger":"manager","msg":"Setting up webhooks"}
{"level":"info","ts":1565407823.8920846,"logger":"manager","msg":"Starting the manager","uuid":"33b9a574-b8c0-11e9-9788-66c5545c5018","namespace":"elastic-system","version":"0.9.0","build_hash":"8280d41","build_date":"2019-07-29T14:26:01Z","build_snapshot":"false"}
{"level":"info","ts":1565407824.195746,"logger":"kubebuilder.webhook","msg":"installing webhook configuration in cluster"}
{"level":"info","ts":1565407824.1992793,"logger":"kubebuilder.controller","msg":"Starting Controller","controller":"apmserver-controller"}
{"level":"info","ts":1565407824.199369,"logger":"kubebuilder.controller","msg":"Starting Controller","controller":"apm-es-association-controller"}
{"level":"info","ts":1565407824.1994004,"logger":"kubebuilder.controller","msg":"Starting Controller","controller":"kibana-association-controller"}
{"level":"info","ts":1565407824.1994479,"logger":"kubebuilder.controller","msg":"Starting Controller","controller":"elasticsearch-controller"}
{"level":"info","ts":1565407824.1994774,"logger":"kubebuilder.controller","msg":"Starting Controller","controller":"kibana-controller"}
{"level":"info","ts":1565407824.1995258,"logger":"kubebuilder.controller","msg":"Starting Controller","controller":"license-controller"}
{"level":"info","ts":1565407824.199554,"logger":"kubebuilder.controller","msg":"Starting Controller","controller":"trial-controller"}
{"level":"info","ts":1565407824.299501,"logger":"kubebuilder.controller","msg":"Starting workers","controller":"kibana-association-controller","worker count":1}
{"level":"info","ts":1565407824.3006725,"logger":"kubebuilder.controller","msg":"Starting workers","controller":"apmserver-controller","worker count":1}
{"level":"info","ts":1565407824.300739,"logger":"kubebuilder.controller","msg":"Starting workers","controller":"apm-es-association-controller","worker count":1}
{"level":"info","ts":1565407824.3007946,"logger":"kubebuilder.controller","msg":"Starting workers","controller":"trial-controller","worker count":1}
{"level":"info","ts":1565407824.3008096,"logger":"kubebuilder.controller","msg":"Starting workers","controller":"elasticsearch-controller","worker count":1}
{"level":"info","ts":1565407824.3008258,"logger":"kubebuilder.controller","msg":"Starting workers","controller":"kibana-controller","worker count":1}
{"level":"info","ts":1565407824.3008394,"logger":"kubebuilder.controller","msg":"Starting workers","controller":"license-controller","worker count":1}
{"level":"info","ts":1565407825.0831032,"logger":"kubebuilder.webhook","msg":"starting the webhook server."}
$