I am running into this error on random pods. Thank you @matthew-l-daniel for the comment - as I didn't know where to start. Here is the contents of /opt/cni/bin on the node

:/opt/cni/bin$ ls bridge host-local loopback

Here are the kubelet logs for a container that failed.

Jan 30 15:42:00 ip-172-20-39-216 kubelet[32233]: E0130 15:42:00.924370 32233 kuberuntime_sandbox.go:54] CreatePodSandbox for pod "postgres-core-0_service-master-459cf23(d8acae2f-24a2-11e9-b79c-0a0d1213cce2)" failed: rpc error: code = Unknown desc = failed to start sandbox container for pod "postgres-core-0": Error response from daemon: grpc: the connection is unavailable Jan 30 15:42:00 ip-172-20-39-216 kubelet[32233]: E0130 15:42:00.924380 32233 kuberuntime_manager.go:647] createPodSandbox for pod "postgres-core-0_service-master-459cf23(d8acae2f-24a2-11e9-b79c-0a0d1213cce2)" failed: rpc error: code = Unknown desc = failed to start sandbox container for pod "postgres-core-0": Error response from daemon: grpc: the connection is unavailable Jan 30 15:42:00 ip-172-20-39-216 kubelet[32233]: E0130 15:42:00.924427 32233 pod_workers.go:186] Error syncing pod d8acae2f-24a2-11e9-b79c-0a0d1213cce2 ("postgres-core-0_service-master-459cf23(d8acae2f-24a2-11e9-b79c-0a0d1213cce2)"), skipping: failed to "CreatePodSandbox" for "postgres-core-0_service-master-459cf23(d8acae2f-24a2-11e9-b79c-0a0d1213cce2)" with CreatePodSandboxError: "CreatePodSandbox for pod \"postgres-core-0_service-master-459cf23(d8acae2f-24a2-11e9-b79c-0a0d1213cce2)\" failed: rpc error: code = Unknown desc = failed to start sandbox container for pod \"postgres-core-0\": Error response from daemon: grpc: the connection is unavailable"

As for flannel container logs, there are many flannel pods running - and all are healthy.

1. Kubernetes v 1.10.11
2. Docker version 17.03.2-ce, build f5ec1e2

Flannel logs

E0130 15:34:16.536354 1 vxlan_network.go:187] DelFDB failed: no such file or directory E0130 15:34:16.536411 1 vxlan_network.go:191] failed to delete vxlanRoute (100.107.178.0/24 -> 100.107.178.0): no such process E0130 17:33:44.848163 1 vxlan_network.go:187] DelFDB failed: no such file or directory E0130 17:33:44.848219 1 vxlan_network.go:191] failed to delete vxlanRoute (100.107.201.0/24 -> 100.107.201.0): no such process