当使用 kubeadm 升级 kubernetes 集群时，运行“kubeadm 升级计划”时看到以下错误。我不确定如何解决这些错误：
I0716 10:45:02.966479 27758 version.go:182] fetching Kubernetes version from URL: https://dl.k8s.io/release/stable.txt
I0716 10:45:03.173334 27758 version.go:251] remote version is much newer: v1.18.6; falling back to: stable-1.17
I0716 10:45:03.173400 27758 version.go:182] fetching Kubernetes version from URL: https://dl.k8s.io/release/stable-1.17.txt
[upgrade/versions] Latest stable version: v1.17.9
context deadline exceeded
[upgrade/versions] FATAL
k8s.io/kubernetes/cmd/kubeadm/app/cmd/upgrade.runPlan
/workspace/anago-v1.17.9-rc.0.37+d1c2f63bd4fc89/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/cmd/kubeadm/app/cmd/upgrade/plan.go:97
k8s.io/kubernetes/cmd/kubeadm/app/cmd/upgrade.NewCmdPlan.func1
/workspace/anago-v1.17.9-rc.0.37+d1c2f63bd4fc89/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/cmd/kubeadm/app/cmd/upgrade/plan.go:55
k8s.io/kubernetes/vendor/github.com/spf13/cobra.(*Command).execute
/workspace/anago-v1.17.9-rc.0.37+d1c2f63bd4fc89/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/vendor/github.com/spf13/cobra/command.go:826
k8s.io/kubernetes/vendor/github.com/spf13/cobra.(*Command).ExecuteC
/workspace/anago-v1.17.9-rc.0.37+d1c2f63bd4fc89/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/vendor/github.com/spf13/cobra/command.go:914
k8s.io/kubernetes/vendor/github.com/spf13/cobra.(*Command).Execute
/workspace/anago-v1.17.9-rc.0.37+d1c2f63bd4fc89/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/vendor/github.com/spf13/cobra/command.go:864
k8s.io/kubernetes/cmd/kubeadm/app.Run
/workspace/anago-v1.17.9-rc.0.37+d1c2f63bd4fc89/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/cmd/kubeadm/app/kubeadm.go:50
main.main
_output/dockerized/go/src/k8s.io/kubernetes/cmd/kubeadm/kubeadm.go:25
runtime.main
/usr/local/go/src/runtime/proc.go:203
runtime.goexit
/usr/local/go/src/runtime/asm_amd64.s:1357