diff --git a/frontend/app/services/hierarchy.service.ts b/frontend/app/services/hierarchy.service.ts
index 53054cc3..c69827d9 100644
--- a/frontend/app/services/hierarchy.service.ts
+++ b/frontend/app/services/hierarchy.service.ts
@@ -37,6 +37,10 @@ export class HierarchyService {
     this.isLoading = false;
   }
 
+  clear(): void {
+    this.warning = '';
+  }
+
   getHierarchyFromZh(zh) {
     if (zh.properties.main_id_rb) {
       this.getHierarchy(zh.properties.id_zh);
diff --git a/frontend/app/zh-forms/tabs/tab0/zh-form-tab0.component.ts b/frontend/app/zh-forms/tabs/tab0/zh-form-tab0.component.ts
index 8ffd8dfe..b0a45bb4 100755
--- a/frontend/app/zh-forms/tabs/tab0/zh-form-tab0.component.ts
+++ b/frontend/app/zh-forms/tabs/tab0/zh-form-tab0.component.ts
@@ -284,7 +284,7 @@ export class ZhFormTab0Component implements OnInit {
   ngOnDestroy() {
     if (this.$_geojsonSub) this.$_geojsonSub.unsubscribe();
     if (this.$_currentZhSub) this.$_currentZhSub.unsubscribe();
-    this.hierarchy.warning = '';
+    this.hierarchy.clear();
   }
 
   featureCollectionToMultipolygon(featureCollection) {
diff --git a/frontend/app/zh-forms/tabs/tab1/zh-form-tab1.component.ts b/frontend/app/zh-forms/tabs/tab1/zh-form-tab1.component.ts
index e45fb962..1d3dd3c4 100755
--- a/frontend/app/zh-forms/tabs/tab1/zh-form-tab1.component.ts
+++ b/frontend/app/zh-forms/tabs/tab1/zh-form-tab1.component.ts
@@ -199,6 +199,6 @@ export class ZhFormTab1Component implements OnInit {
   ngOnDestroy() {
     if (this.$_currentZhSub) this.$_currentZhSub.unsubscribe();
     this.ngbModal.dismissAll();
-    this.hierarchy.warning = '';
+    this.hierarchy.clear();
   }
 }
diff --git a/frontend/app/zh-forms/tabs/tab2/zh-form-tab2.component.ts b/frontend/app/zh-forms/tabs/tab2/zh-form-tab2.component.ts
index 67a9e197..c22e54d5 100755
--- a/frontend/app/zh-forms/tabs/tab2/zh-form-tab2.component.ts
+++ b/frontend/app/zh-forms/tabs/tab2/zh-form-tab2.component.ts
@@ -141,6 +141,6 @@ export class ZhFormTab2Component implements OnInit, AfterViewInit {
   ngOnDestroy() {
     if (this.$_currentZhSub) this.$_currentZhSub.unsubscribe();
     if (this.$_fromChangeSub) this.$_fromChangeSub.unsubscribe();
-    this.hierarchy.warning = '';
+    this.hierarchy.clear();
   }
 }
diff --git a/frontend/app/zh-forms/tabs/tab3/zh-form-tab3.component.ts b/frontend/app/zh-forms/tabs/tab3/zh-form-tab3.component.ts
index 059ea6ac..bb1e8dbe 100755
--- a/frontend/app/zh-forms/tabs/tab3/zh-form-tab3.component.ts
+++ b/frontend/app/zh-forms/tabs/tab3/zh-form-tab3.component.ts
@@ -471,6 +471,6 @@ export class ZhFormTab3Component implements OnInit {
   ngOnDestroy() {
     if (this.$_currentZhSub) this.$_currentZhSub.unsubscribe();
     if (this.$_fromChangeSub) this.$_fromChangeSub.unsubscribe();
-    this.hierarchy.warning = '';
+    this.hierarchy.clear();
   }
 }
diff --git a/frontend/app/zh-forms/tabs/tab4/zh-form-tab4.component.ts b/frontend/app/zh-forms/tabs/tab4/zh-form-tab4.component.ts
index 6e48f470..ceb55322 100755
--- a/frontend/app/zh-forms/tabs/tab4/zh-form-tab4.component.ts
+++ b/frontend/app/zh-forms/tabs/tab4/zh-form-tab4.component.ts
@@ -475,6 +475,6 @@ export class ZhFormTab4Component implements OnInit {
   }
 
   ngOnDestroy() {
-    this.hierarchy.warning = '';
+    this.hierarchy.clear();
   }
 }
diff --git a/frontend/app/zh-forms/tabs/tab5/zh-form-tab5.component.ts b/frontend/app/zh-forms/tabs/tab5/zh-form-tab5.component.ts
index 212d1e57..4aaf22df 100755
--- a/frontend/app/zh-forms/tabs/tab5/zh-form-tab5.component.ts
+++ b/frontend/app/zh-forms/tabs/tab5/zh-form-tab5.component.ts
@@ -1180,6 +1180,6 @@ export class ZhFormTab5Component implements OnInit {
   ngOnDestroy() {
     if (this.$_getTabChangeSub) this.$_getTabChangeSub.unsubscribe();
     if (this.$_currentZhSub) this.$_currentZhSub.unsubscribe();
-    this.hierarchy.warning = '';
+    this.hierarchy.clear();
   }
 }
diff --git a/frontend/app/zh-forms/tabs/tab6/zh-form-tab6.component.ts b/frontend/app/zh-forms/tabs/tab6/zh-form-tab6.component.ts
index 98e48b67..6c5a2523 100755
--- a/frontend/app/zh-forms/tabs/tab6/zh-form-tab6.component.ts
+++ b/frontend/app/zh-forms/tabs/tab6/zh-form-tab6.component.ts
@@ -1021,6 +1021,6 @@ export class ZhFormTab6Component implements OnInit {
   ngOnDestroy() {
     if (this.$_getTabChangeSub) this.$_getTabChangeSub.unsubscribe();
     if (this.$_currentZhSub) this.$_currentZhSub.unsubscribe();
-    this.hierarchy.warning = '';
+    this.hierarchy.clear();
   }
 }
diff --git a/frontend/app/zh-forms/tabs/tab7/zh-form-tab7.component.ts b/frontend/app/zh-forms/tabs/tab7/zh-form-tab7.component.ts
index 4e4dab40..a5c87603 100755
--- a/frontend/app/zh-forms/tabs/tab7/zh-form-tab7.component.ts
+++ b/frontend/app/zh-forms/tabs/tab7/zh-form-tab7.component.ts
@@ -492,6 +492,6 @@ export class ZhFormTab7Component implements OnInit {
   ngOnDestroy() {
     if (this.$_getTabChangeSub) this.$_getTabChangeSub.unsubscribe();
     if (this.$_currentZhSub) this.$_currentZhSub.unsubscribe();
-    this.hierarchy.warning = '';
+    this.hierarchy.clear();
   }
 }
diff --git a/frontend/app/zh-forms/tabs/tab9/zh-form-tab9.component.ts b/frontend/app/zh-forms/tabs/tab9/zh-form-tab9.component.ts
index 7fe8878b..f914dc51 100755
--- a/frontend/app/zh-forms/tabs/tab9/zh-form-tab9.component.ts
+++ b/frontend/app/zh-forms/tabs/tab9/zh-form-tab9.component.ts
@@ -51,6 +51,6 @@ export class ZhFormTab9Component implements OnInit {
   ngOnDestroy() {
     if (this.$_getTabChangeSub) this.$_getTabChangeSub.unsubscribe();
     if (this.$_currentZhSub) this.$_currentZhSub.unsubscribe();
-    this.hierarchy.warning = '';
+    this.hierarchy.clear();
   }
 }