diff --git a/apier/v1/attributes_it_test.go b/apier/v1/attributes_it_test.go
index c85086f99..2fdff8fb6 100644
--- a/apier/v1/attributes_it_test.go
+++ b/apier/v1/attributes_it_test.go
@@ -54,6 +54,7 @@ var sTestsAlsPrf = []func(t *testing.T){
 	testAttributeSGetAttributeForEventNotFound,
 	testAttributeSGetAttributeForEventWithMetaAnyContext,
 	testAttributeSProcessEvent,
+	testAttributeSProcessEventMissing,
 	testAttributeSProcessEventWithNoneSubstitute,
 	testAttributeSProcessEventWithNoneSubstitute2,
 	testAttributeSProcessEventWithNoneSubstitute3,
@@ -349,6 +350,24 @@ func testAttributeSProcessEvent(t *testing.T) {
 	}
 }
 
+func testAttributeSProcessEventMissing(t *testing.T) {
+	ev := &utils.CGREvent{
+		Tenant:  "cgrates.org",
+		ID:      "testAttributeSProcessEvent",
+		Context: utils.StringPointer(utils.MetaSessionS),
+		Event: map[string]interface{}{
+			utils.Account:     "NonExist",
+			utils.Category:    "*attributes",
+			utils.Destination: "+491511231234",
+		},
+	}
+	var rplyEv engine.AttrSProcessEventReply
+	if err := attrSRPC.Call(utils.AttributeSv1ProcessEvent,
+		ev, &rplyEv); err == nil && err != utils.ErrMandatoryIeMissing {
+		t.Error(err)
+	}
+}
+
 func testAttributeSProcessEventWithNoneSubstitute(t *testing.T) {
 	ev := &utils.CGREvent{
 		Tenant:  "cgrates.org",
diff --git a/engine/attributes.go b/engine/attributes.go
index 0f350c189..92549340f 100644
--- a/engine/attributes.go
+++ b/engine/attributes.go
@@ -165,6 +165,15 @@ func (alS *AttributeService) processEvent(args *AttrArgsProcessEvent) (
 	rply *AttrSProcessEventReply, err error) {
 	attrPrf, err := alS.attributeProfileForEvent(args)
 	if err != nil {
+		if err == utils.ErrNotFound {
+			// change the error in case that at least one field need to be processed by attributes
+			for _, valIface := range args.CGREvent.Event {
+				if valIface == interface{}(utils.MetaAttributes) {
+					err = utils.ErrMandatoryIeMissing
+					break
+				}
+			}
+		}
 		return nil, err
 	}
 	rply = &AttrSProcessEventReply{
@@ -204,11 +213,12 @@ func (alS *AttributeService) processEvent(args *AttrArgsProcessEvent) (
 	}
 	for _, valIface := range rply.CGREvent.Event {
 		if valIface == interface{}(utils.MetaAttributes) {
+			// mandatory IE missing
 			return nil, utils.NewCGRError(
 				utils.AttributeSv1ProcessEvent,
-				utils.AttributesNotFound,
-				utils.AttributesNotFound,
-				utils.AttributesNotFound)
+				utils.ErrMandatoryIeMissing.Error(),
+				utils.ErrMandatoryIeMissing.Error(),
+				utils.ErrMandatoryIeMissing.Error())
 		}
 	}
 	return
@@ -239,7 +249,7 @@ func (alS *AttributeService) V1ProcessEvent(args *AttrArgsProcessEvent,
 	for i := 0; i < *args.ProcessRuns; i++ {
 		evRply, err := alS.processEvent(args)
 		if err != nil {
-			if err != utils.ErrNotFound {
+			if err != utils.ErrNotFound && err != utils.ErrMandatoryIeMissing {
 				err = utils.NewErrServerError(err)
 			} else if i != 0 { // ignore "not found" in a loop different than 0
 				err = nil
diff --git a/engine/stats_metrics.go b/engine/stats_metrics.go
index ede4b453c..12654bb00 100644
--- a/engine/stats_metrics.go
+++ b/engine/stats_metrics.go
@@ -30,6 +30,8 @@ type Metric interface {
 	GetValue() float64
 }
 
+// Old metric (deprecated)
+// New mtric are in statmetrics.go
 const ASR = "ASR"
 const ACD = "ACD"
 const TCD = "TCD"