diff --git a/src/views/dashboard/configuration/widget/graph-styles/components/ValueMappings.vue b/src/views/dashboard/configuration/widget/graph-styles/components/ValueMappings.vue
index 9c45ddd7..99d2ae90 100644
--- a/src/views/dashboard/configuration/widget/graph-styles/components/ValueMappings.vue
+++ b/src/views/dashboard/configuration/widget/graph-styles/components/ValueMappings.vue
@@ -56,6 +56,9 @@ limitations under the License. -->
     }
     delete valueMappings.value[list[index]];
     keys.value = Object.keys(valueMappings.value);
+    if (!keys.value.length) {
+      keys.value = [""];
+    }
     updateConfig();
   }