diff --git a/Dockerfile b/Dockerfile
index 91773e1..fc065ce 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -10,6 +10,6 @@ LABEL maintainer="Bo-Yi Wu <appleboy.tw@gmail.com>"
 ADD config/config.yml /
 ADD bin/gorush /
 
-EXPOSE 8088
+EXPOSE 8088 9000
 ENTRYPOINT ["/gorush"]
 CMD ["-c", "config.yml"]
diff --git a/Dockerfile.arm b/Dockerfile.arm
index 9c7be04..f8470c8 100644
--- a/Dockerfile.arm
+++ b/Dockerfile.arm
@@ -10,6 +10,6 @@ LABEL maintainer="Bo-Yi Wu <appleboy.tw@gmail.com>"
 ADD config/config.yml /
 ADD bin/gorush-arm /gorush
 
-EXPOSE 8088
+EXPOSE 8088 9000
 ENTRYPOINT ["/gorush"]
 CMD ["-c", "config.yml"]
diff --git a/Dockerfile.arm64 b/Dockerfile.arm64
index 6fb54e6..be5fdba 100644
--- a/Dockerfile.arm64
+++ b/Dockerfile.arm64
@@ -10,6 +10,6 @@ LABEL maintainer="Bo-Yi Wu <appleboy.tw@gmail.com>"
 ADD config/config.yml /
 ADD bin/gorush-arm64 /gorush
 
-EXPOSE 8088
+EXPOSE 8088 9000
 ENTRYPOINT ["/gorush"]
 CMD ["-c", "config.yml"]
diff --git a/README.md b/README.md
index 2252ecc..59ac1c5 100644
--- a/README.md
+++ b/README.md
@@ -92,7 +92,7 @@ core:
 
 grpc:
   enabled: false # enabale gRPC server
-  port: 50051
+  port: 9000
 
 api:
   push_uri: "/api/push"
@@ -675,7 +675,7 @@ import (
 )
 
 const (
-	address = "localhost:50051"
+	address = "localhost:9000"
 )
 
 func main() {
@@ -710,7 +710,7 @@ var services = require('./gorush_grpc_pb');
 var grpc = require('grpc');
 
 function main() {
-  var client = new services.GorushClient('localhost:50051',
+  var client = new services.GorushClient('localhost:9000',
     grpc.credentials.createInsecure());
   var request = new messages.NotificationRequest();
   request.setPlatform(2);
diff --git a/config/config.go b/config/config.go
index d3f25cf..0cc8162 100644
--- a/config/config.go
+++ b/config/config.go
@@ -188,7 +188,7 @@ func BuildDefaultPushConf() ConfYaml {
 
 	// gRPC Server
 	conf.GRPC.Enabled = false
-	conf.GRPC.Port = "50051"
+	conf.GRPC.Port = "9000"
 	return conf
 }
 
diff --git a/config/config.yml b/config/config.yml
index cdc5a4d..2db1377 100644
--- a/config/config.yml
+++ b/config/config.yml
@@ -22,7 +22,7 @@ core:
 
 grpc:
   enabled: false # enabale gRPC server
-  port: 50051
+  port: 9000
 
 api:
   push_uri: "/api/push"
diff --git a/config/config_test.go b/config/config_test.go
index a4bc43a..a69efae 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -119,7 +119,7 @@ func (suite *ConfigTestSuite) TestValidateConfDefault() {
 
 	// gRPC
 	assert.Equal(suite.T(), false, suite.ConfGorushDefault.GRPC.Enabled)
-	assert.Equal(suite.T(), "50051", suite.ConfGorushDefault.GRPC.Port)
+	assert.Equal(suite.T(), "9000", suite.ConfGorushDefault.GRPC.Port)
 }
 
 func (suite *ConfigTestSuite) TestValidateConf() {
@@ -184,7 +184,7 @@ func (suite *ConfigTestSuite) TestValidateConf() {
 
 	// gRPC
 	assert.Equal(suite.T(), false, suite.ConfGorush.GRPC.Enabled)
-	assert.Equal(suite.T(), "50051", suite.ConfGorush.GRPC.Port)
+	assert.Equal(suite.T(), "9000", suite.ConfGorush.GRPC.Port)
 }
 
 func TestConfigTestSuite(t *testing.T) {
diff --git a/rpc/example/go/client.go b/rpc/example/go/client.go
index 2c6b1c3..254621a 100644
--- a/rpc/example/go/client.go
+++ b/rpc/example/go/client.go
@@ -9,7 +9,7 @@ import (
 )
 
 const (
-	address = "localhost:50051"
+	address = "localhost:9000"
 )
 
 func main() {
diff --git a/rpc/example/node/client.js b/rpc/example/node/client.js
index 2965910..81cdfc2 100644
--- a/rpc/example/node/client.js
+++ b/rpc/example/node/client.js
@@ -4,7 +4,7 @@ var services = require('./gorush_grpc_pb');
 var grpc = require('grpc');
 
 function main() {
-  var client = new services.GorushClient('localhost:50051',
+  var client = new services.GorushClient('localhost:9000',
     grpc.credentials.createInsecure());
   var request = new messages.NotificationRequest();
   request.setPlatform(2);
diff --git a/rpc/server.go b/rpc/server.go
index 17ee111..682c846 100644
--- a/rpc/server.go
+++ b/rpc/server.go
@@ -12,7 +12,7 @@ import (
 )
 
 const (
-	port = ":50051"
+	port = ":9000"
 )
 
 // server is used to implement gorush grpc server.
@@ -46,7 +46,7 @@ func RunGRPCServer() error {
 
 	lis, err := net.Listen("tcp", ":"+gorush.PushConf.GRPC.Port)
 	if err != nil {
-		gorush.LogError.Error("failed to listen: %v", err)
+		gorush.LogError.Errorf("failed to listen: %v", err)
 		return err
 	}
 	s := grpc.NewServer()
@@ -55,7 +55,7 @@ func RunGRPCServer() error {
 	reflection.Register(s)
 	gorush.LogAccess.Debug("gRPC server is running on " + gorush.PushConf.GRPC.Port + " port.")
 	if err := s.Serve(lis); err != nil {
-		gorush.LogError.Error("failed to serve: %v", err)
+		gorush.LogError.Errorf("failed to serve: %v", err)
 		return err
 	}