node-driver-registrar: Node driver registrar says "Lost connection" and do nothing

Log:

I0323 21:20:55.915743       1 main.go:110] Version: unknown
I0323 21:20:55.915816       1 main.go:120] Attempting to open a gRPC connection with: "/csi/csi.sock"
I0323 21:20:55.915833       1 connection.go:151] Connecting to unix:///csi/csi.sock
I0323 21:20:55.916332       1 main.go:127] Calling CSI driver to discover driver name
I0323 21:20:55.916348       1 connection.go:180] GRPC call: /csi.v1.Identity/GetPluginInfo
I0323 21:20:55.916354       1 connection.go:181] GRPC request: {}
I0323 21:20:55.917907       1 connection.go:183] GRPC response: {"name":"x","vendor_version":"0.3.0"}
I0323 21:20:55.918413       1 connection.go:184] GRPC error: <nil>
I0323 21:20:55.918421       1 main.go:137] CSI driver name: "x"
I0323 21:20:55.918477       1 node_register.go:58] Starting Registration Server at: /registration/x-reg.sock
I0323 21:20:55.918603       1 node_register.go:67] Registration Server started at: /registration/x-reg.sock
I0323 21:20:57.567609       1 main.go:77] Received GetInfo call: &InfoRequest{}
I0323 21:20:57.671681       1 main.go:87] Received NotifyRegistrationStatus call: &RegistrationStatus{PluginRegistered:true,Error:,}
E0323 21:21:15.690492       1 connection.go:129] Lost connection to unix:///csi/csi.sock.

After restart container, it works.