diff --git a/app/assets/javascripts/issue_show/components/description.vue b/app/assets/javascripts/issue_show/components/description.vue
index 4443d6c6760..d5b355a39a2 100644
--- a/app/assets/javascripts/issue_show/components/description.vue
+++ b/app/assets/javascripts/issue_show/components/description.vue
@@ -1,5 +1,6 @@
 <script>
 import $ from 'jquery';
+import createFlash from '~/flash';
 import animateMixin from '../mixins/animate';
 import TaskList from '../../task_list';
 import recaptchaModalImplementor from '../../vue_shared/mixins/recaptcha_modal_implementor';
@@ -89,7 +90,7 @@ export default {
     },
 
     taskListUpdateError(data) {
-      // stub for error handling
+      createFlash(data.errors[0]);
     },
 
     updateTaskStatusText() {
diff --git a/app/assets/javascripts/task_list.js b/app/assets/javascripts/task_list.js
index f063250c36f..fce41ef65c4 100644
--- a/app/assets/javascripts/task_list.js
+++ b/app/assets/javascripts/task_list.js
@@ -44,12 +44,12 @@ export default class TaskList {
     const patchData = {};
     patchData[this.dataType] = {
       [this.fieldName]: $target.val(),
-      ['lock_version']: this.lockVersion,
+      lock_version: this.lockVersion,
     };
 
     return axios
       .patch($target.data('updateUrl') || $('form.js-issuable-update').attr('action'), patchData)
       .then(({ data }) => this.onSuccess(data))
-      .catch(err => this.onError(err));
+      .catch(({ response }) => this.onError(response.data));
   }
 }