diff --git a/api/feature.go b/api/feature.go
index 258322e..f370674 100644
--- a/api/feature.go
+++ b/api/feature.go
@@ -57,8 +57,8 @@ type FeatureLocalInterface interface {
 	// SetWritePermissionCheckCallback being invoked by the stack returning wether
 	// the remote requested write command shall be allowed or not
 	//
-	// reason contains the error string reported back when write is not allwed
-	ApproveOrDenyWrite(msg *Message, allow bool, reason string)
+	// ErrorType.ErrorNumber should be 0 if write is allowed
+	ApproveOrDenyWrite(msg *Message, err model.ErrorType)
 	// Overwrite the default 1 minute timeout for write approvals
 	SetWriteApprovalTimeout(duration time.Duration)
 
diff --git a/spine/feature_local.go b/spine/feature_local.go
index 401220c..65e072e 100644
--- a/spine/feature_local.go
+++ b/spine/feature_local.go
@@ -182,7 +182,7 @@ func (r *FeatureLocal) addPendingApproval(msg *api.Message) {
 	r.muxResponseCB.Unlock()
 }
 
-func (r *FeatureLocal) ApproveOrDenyWrite(msg *api.Message, allow bool, reason string) {
+func (r *FeatureLocal) ApproveOrDenyWrite(msg *api.Message, err model.ErrorType) {
 	if r.Role() != model.RoleTypeServer {
 		return
 	}
@@ -198,13 +198,12 @@ func (r *FeatureLocal) ApproveOrDenyWrite(msg *api.Message, allow bool, reason s
 
 	timer.Stop()
 
-	if allow {
+	if err.ErrorNumber == 0 {
 		r.processWrite(msg)
 		return
 	}
 
-	err := model.NewErrorTypeFromString(reason)
-	_ = msg.FeatureRemote.Device().Sender().ResultError(msg.RequestHeader, r.Address(), err)
+	_ = msg.FeatureRemote.Device().Sender().ResultError(msg.RequestHeader, r.Address(), &err)
 }
 
 func (r *FeatureLocal) SetWriteApprovalTimeout(duration time.Duration) {
diff --git a/spine/feature_local_test.go b/spine/feature_local_test.go
index 1353eb0..e3072d6 100644
--- a/spine/feature_local_test.go
+++ b/spine/feature_local_test.go
@@ -379,7 +379,10 @@ func (suite *DeviceClassificationTestSuite) Test_SetWriteApprovalCallback_Invali
 	cb := func(msg *api.Message) {}
 	err := suite.localFeature.AddWriteApprovalCallback(cb)
 	assert.NotNil(suite.T(), err)
-	suite.localFeature.ApproveOrDenyWrite(&api.Message{}, true, "")
+	result := model.ErrorType{
+		ErrorNumber: 0,
+	}
+	suite.localFeature.ApproveOrDenyWrite(&api.Message{}, result)
 }
 
 func (suite *DeviceClassificationTestSuite) Test_AddPendingApproval_Invalid() {
@@ -412,7 +415,10 @@ func (suite *DeviceClassificationTestSuite) Test_Write_Callback() {
 	}
 
 	cb := func(msg *api.Message) {
-		suite.localServerFeatureWrite.ApproveOrDenyWrite(msg, true, "")
+		result := model.ErrorType{
+			ErrorNumber: 0,
+		}
+		suite.localServerFeatureWrite.ApproveOrDenyWrite(msg, result)
 	}
 
 	suite.localServerFeatureWrite.AddWriteApprovalCallback(cb)
@@ -422,7 +428,11 @@ func (suite *DeviceClassificationTestSuite) Test_Write_Callback() {
 	suite.senderMock.EXPECT().ResultError(mock.Anything, mock.Anything, mock.Anything).Return(nil).Once()
 
 	cb = func(msg *api.Message) {
-		suite.localServerFeatureWrite.ApproveOrDenyWrite(msg, false, "not allowed by application")
+		result := model.ErrorType{
+			ErrorNumber: 7,
+			Description: util.Ptr(model.DescriptionType("not allowed by application")),
+		}
+		suite.localServerFeatureWrite.ApproveOrDenyWrite(msg, result)
 	}
 
 	suite.localServerFeatureWrite.AddWriteApprovalCallback(cb)
@@ -451,7 +461,10 @@ func (suite *DeviceClassificationTestSuite) Test_Write_Callback_Timeout() {
 
 	cb := func(msg *api.Message) {
 		time.Sleep(time.Second * 1)
-		suite.localServerFeatureWrite.ApproveOrDenyWrite(msg, true, "")
+		result := model.ErrorType{
+			ErrorNumber: 0,
+		}
+		suite.localServerFeatureWrite.ApproveOrDenyWrite(msg, result)
 	}
 
 	suite.localServerFeatureWrite.AddWriteApprovalCallback(cb)