diff --git a/Cargo.lock b/Cargo.lock
index 525c767..2385a2c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -160,7 +160,7 @@ dependencies = [
 
 [[package]]
 name = "dragonfly-api"
-version = "2.0.133"
+version = "2.0.134"
 dependencies = [
  "prost 0.11.9",
  "prost-types 0.13.1",
diff --git a/Cargo.toml b/Cargo.toml
index 0df99e9..2b3dca2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "dragonfly-api"
-version = "2.0.133"
+version = "2.0.134"
 authors = ["Gaius <gaius.qi@gmail.com>"]
 edition = "2021"
 license = "Apache-2.0"
diff --git a/pkg/apis/errordetails/v2/errordetails.pb.go b/pkg/apis/errordetails/v2/errordetails.pb.go
index c102127..54c7e87 100644
--- a/pkg/apis/errordetails/v2/errordetails.pb.go
+++ b/pkg/apis/errordetails/v2/errordetails.pb.go
@@ -47,7 +47,7 @@ type Backend struct {
 	// Backend HTTP response header.
 	Header map[string]string `protobuf:"bytes,2,rep,name=header,proto3" json:"header,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
 	// Backend HTTP status code.
-	StatusCode int32 `protobuf:"varint,3,opt,name=status_code,json=statusCode,proto3" json:"status_code,omitempty"`
+	StatusCode *int32 `protobuf:"varint,3,opt,name=status_code,json=statusCode,proto3,oneof" json:"status_code,omitempty"`
 }
 
 func (x *Backend) Reset() {
@@ -97,8 +97,8 @@ func (x *Backend) GetHeader() map[string]string {
 }
 
 func (x *Backend) GetStatusCode() int32 {
-	if x != nil {
-		return x.StatusCode
+	if x != nil && x.StatusCode != nil {
+		return *x.StatusCode
 	}
 	return 0
 }
@@ -111,24 +111,25 @@ var file_pkg_apis_errordetails_v2_errordetails_proto_rawDesc = []byte{
 	0x64, 0x65, 0x74, 0x61, 0x69, 0x6c, 0x73, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x12, 0x0f, 0x65,
 	0x72, 0x72, 0x6f, 0x72, 0x64, 0x65, 0x74, 0x61, 0x69, 0x6c, 0x73, 0x2e, 0x76, 0x32, 0x1a, 0x17,
 	0x76, 0x61, 0x6c, 0x69, 0x64, 0x61, 0x74, 0x65, 0x2f, 0x76, 0x61, 0x6c, 0x69, 0x64, 0x61, 0x74,
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+	0x65, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x22, 0xe0, 0x01, 0x0a, 0x07, 0x42, 0x61, 0x63, 0x6b,
 	0x65, 0x6e, 0x64, 0x12, 0x18, 0x0a, 0x07, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x18, 0x01,
 	0x20, 0x01, 0x28, 0x09, 0x52, 0x07, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x12, 0x3c, 0x0a,
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-	0x6f, 0x33,
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+	0x52, 0x0a, 0x73, 0x74, 0x61, 0x74, 0x75, 0x73, 0x43, 0x6f, 0x64, 0x65, 0x88, 0x01, 0x01, 0x1a,
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+	0x0a, 0x03, 0x6b, 0x65, 0x79, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x03, 0x6b, 0x65, 0x79,
+	0x12, 0x14, 0x0a, 0x05, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x18, 0x02, 0x20, 0x01, 0x28, 0x09, 0x52,
+	0x05, 0x76, 0x61, 0x6c, 0x75, 0x65, 0x3a, 0x02, 0x38, 0x01, 0x42, 0x0e, 0x0a, 0x0c, 0x5f, 0x73,
+	0x74, 0x61, 0x74, 0x75, 0x73, 0x5f, 0x63, 0x6f, 0x64, 0x65, 0x42, 0x35, 0x5a, 0x33, 0x64, 0x37,
+	0x79, 0x2e, 0x69, 0x6f, 0x2f, 0x61, 0x70, 0x69, 0x2f, 0x76, 0x32, 0x2f, 0x70, 0x6b, 0x67, 0x2f,
+	0x61, 0x70, 0x69, 0x73, 0x2f, 0x65, 0x72, 0x72, 0x6f, 0x72, 0x64, 0x65, 0x74, 0x61, 0x69, 0x6c,
+	0x73, 0x2f, 0x76, 0x32, 0x3b, 0x65, 0x72, 0x72, 0x6f, 0x72, 0x64, 0x65, 0x74, 0x61, 0x69, 0x6c,
+	0x73, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
@@ -176,6 +177,7 @@ func file_pkg_apis_errordetails_v2_errordetails_proto_init() {
 			}
 		}
 	}
+	file_pkg_apis_errordetails_v2_errordetails_proto_msgTypes[0].OneofWrappers = []interface{}{}
 	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
diff --git a/pkg/apis/errordetails/v2/errordetails.pb.validate.go b/pkg/apis/errordetails/v2/errordetails.pb.validate.go
index d87206a..0b12f41 100644
--- a/pkg/apis/errordetails/v2/errordetails.pb.validate.go
+++ b/pkg/apis/errordetails/v2/errordetails.pb.validate.go
@@ -60,15 +60,23 @@ func (m *Backend) validate(all bool) error {
 
 	// no validation rules for Header
 
-	if val := m.GetStatusCode(); val < 100 || val >= 599 {
-		err := BackendValidationError{
-			field:  "StatusCode",
-			reason: "value must be inside range [100, 599)",
+	if m.StatusCode != nil {
+
+		if m.GetStatusCode() != 0 {
+
+			if val := m.GetStatusCode(); val < 100 || val >= 599 {
+				err := BackendValidationError{
+					field:  "StatusCode",
+					reason: "value must be inside range [100, 599)",
+				}
+				if !all {
+					return err
+				}
+				errors = append(errors, err)
+			}
+
 		}
-		if !all {
-			return err
-		}
-		errors = append(errors, err)
+
 	}
 
 	if len(errors) > 0 {
diff --git a/pkg/apis/errordetails/v2/errordetails.proto b/pkg/apis/errordetails/v2/errordetails.proto
index 86e7319..fccb666 100644
--- a/pkg/apis/errordetails/v2/errordetails.proto
+++ b/pkg/apis/errordetails/v2/errordetails.proto
@@ -29,6 +29,6 @@ message Backend {
   // Backend HTTP response header.
   map<string, string> header = 2;
   // Backend HTTP status code.
-  int32 status_code = 3 [(validate.rules).int32 = {gte: 100, lt: 599}];
+  optional int32 status_code = 3 [(validate.rules).int32 = {gte: 100, lt: 599, ignore_empty: true}];
 }
 
diff --git a/proto/errordetails.proto b/proto/errordetails.proto
index c1fd436..63decaa 100644
--- a/proto/errordetails.proto
+++ b/proto/errordetails.proto
@@ -25,5 +25,5 @@ message Backend {
   // Backend HTTP response header.
   map<string, string> header = 2;
   // Backend HTTP status code.
-  int32 status_code = 3;
+  optional int32 status_code = 3;
 }
diff --git a/src/descriptor.bin b/src/descriptor.bin
index c01baa6..6cc1272 100644
Binary files a/src/descriptor.bin and b/src/descriptor.bin differ
diff --git a/src/errordetails.v2.rs b/src/errordetails.v2.rs
index 9179f96..3ba29c7 100644
--- a/src/errordetails.v2.rs
+++ b/src/errordetails.v2.rs
@@ -13,6 +13,6 @@ pub struct Backend {
         ::prost::alloc::string::String,
     >,
     /// Backend HTTP status code.
-    #[prost(int32, tag = "3")]
-    pub status_code: i32,
+    #[prost(int32, optional, tag = "3")]
+    pub status_code: ::core::option::Option<i32>,
 }