diff --git a/app/observatory/observer.go b/app/observatory/observer.go
index e578be1c7..60b35d715 100644
--- a/app/observatory/observer.go
+++ b/app/observatory/observer.go
@@ -1,3 +1,5 @@
+// +build !confonly
+
 package observatory
 
 import (
diff --git a/go.sum b/go.sum
index 3e676dd3b..ad14004eb 100644
--- a/go.sum
+++ b/go.sum
@@ -325,6 +325,7 @@ google.golang.org/protobuf v1.22.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2
 google.golang.org/protobuf v1.23.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
 google.golang.org/protobuf v1.23.1-0.20200526195155-81db48ad09cc/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
 google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
+google.golang.org/protobuf v1.25.1-0.20200805231151-a709e31e5d12 h1:OwhZOOMuf7leLaSCuxtQ9FW7ui2L2L6UKOtKAUqovUQ=
 google.golang.org/protobuf v1.25.1-0.20200805231151-a709e31e5d12/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
 google.golang.org/protobuf v1.26.0 h1:bxAC2xTBsZGibn2RTntX0oH50xLsqy1OxA9tTL3p/lk=
diff --git a/infra/conf/services.go b/infra/conf/services.go
index bbeba19d2..bbc2e1903 100644
--- a/infra/conf/services.go
+++ b/infra/conf/services.go
@@ -1,7 +1,6 @@
 package conf
 
 import (
-	"bytes"
 	"encoding/json"
 	"github.com/golang/protobuf/jsonpb"
 	"github.com/jhump/protoreflect/desc"
@@ -13,13 +12,13 @@ func (c *Config) BuildServices(service map[string]*json.RawMessage) ([]*serial.T
 	var ret []*serial.TypedMessage
 	for k, v := range service {
 		message, err := desc.LoadMessageDescriptor(k)
-		if err != nil {
+		if err != nil || message == nil {
 			return nil, newError("Cannot find service", k, "").Base(err)
 		}
 
 		serviceConfig := dynamic.NewMessage(message)
 
-		if err := jsonpb.Unmarshal(bytes.NewReader(*v), serviceConfig); err != nil {
+		if err := serviceConfig.UnmarshalJSONPB(&jsonpb.Unmarshaler{AllowUnknownFields: false}, *v); err != nil {
 			return nil, newError("Cannot interpret service configure file", k, "").Base(err)
 		}
 
diff --git a/infra/conf/v2ray.go b/infra/conf/v2ray.go
index 6d6c4259d..0843bc418 100644
--- a/infra/conf/v2ray.go
+++ b/infra/conf/v2ray.go
@@ -2,6 +2,8 @@ package conf
 
 import (
 	"encoding/json"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoregistry"
 	"log"
 	"os"
 	"strings"
@@ -575,7 +577,18 @@ func (c *Config) Build() (*core.Config, error) {
 		developererr := newError("Loading a V2Ray Features as a service is intended for developers only. " +
 			"This is used for developers to prototype new features or for an advanced client to use special features in V2Ray," +
 			" instead of allowing end user to enable it without special tool and knowledge.")
-		return nil, newError("Cannot load service").Base(developererr).Base(err)
+		sb := strings.Builder{}
+		protoregistry.GlobalTypes.RangeMessages(func(messageType protoreflect.MessageType) bool {
+			switch d := messageType.Descriptor().(type) {
+			case protoreflect.MessageDescriptor:
+				sb.WriteString(string(d.Name()))
+				sb.WriteString(":")
+				sb.WriteString(string(d.FullName()))
+				sb.WriteString("\n")
+			}
+			return true
+		})
+		return nil, newError("Cannot load service").Base(developererr).Base(err).Base(newError(sb.String()))
 	} else {
 		config.App = append(config.App, msg...)
 	}
diff --git a/main/distro/all/all.go b/main/distro/all/all.go
index 8e1528404..3417b55f9 100644
--- a/main/distro/all/all.go
+++ b/main/distro/all/all.go
@@ -26,6 +26,9 @@ import (
 	// Fix dependency cycle caused by core import in internet package
 	_ "github.com/v2fly/v2ray-core/v4/transport/internet/tagged/taggedimpl"
 
+	// Developer preview features
+	_ "github.com/v2fly/v2ray-core/v4/app/observatory"
+
 	// Inbound and outbound proxies.
 	_ "github.com/v2fly/v2ray-core/v4/proxy/blackhole"
 	_ "github.com/v2fly/v2ray-core/v4/proxy/dns"