diff --git a/client/src/app/site/topics/components/topic-detail/topic-detail.component.ts b/client/src/app/site/topics/components/topic-detail/topic-detail.component.ts
index f8f3bd738..4a83fbb86 100644
--- a/client/src/app/site/topics/components/topic-detail/topic-detail.component.ts
+++ b/client/src/app/site/topics/components/topic-detail/topic-detail.component.ts
@@ -5,13 +5,13 @@ import { Title, DomSanitizer, SafeHtml } from '@angular/platform-browser';
 import { MatSnackBar } from '@angular/material/snack-bar';
 
 import { TranslateService } from '@ngx-translate/core';
+import { BehaviorSubject } from 'rxjs';
 
 import { BaseViewComponent } from 'app/site/base/base-view';
 import { PromptService } from 'app/core/ui-services/prompt.service';
 import { TopicRepositoryService } from 'app/core/repositories/topics/topic-repository.service';
 import { ViewTopic } from '../../models/view-topic';
 import { OperatorService } from 'app/core/core-services/operator.service';
-import { BehaviorSubject } from 'rxjs';
 import { ItemVisibilityChoices } from 'app/shared/models/agenda/item';
 import { CreateTopic } from '../../models/create-topic';
 import { Topic } from 'app/shared/models/topics/topic';
@@ -110,7 +110,11 @@ export class TopicDetailComponent extends BaseViewComponent {
      * Save a new topic as agenda item
      */
     public async saveTopic(): Promise<void> {
-        if (this.newTopic && this.topicForm.valid) {
+        if (!this.topicForm.valid) {
+            return;
+        }
+
+        if (this.newTopic) {
             if (!this.topicForm.value.agenda_parent_id) {
                 delete this.topicForm.value.agenda_parent_id;
             }
diff --git a/client/src/app/site/users/components/group-list/group-list.component.html b/client/src/app/site/users/components/group-list/group-list.component.html
index a722ce873..3a0a55461 100644
--- a/client/src/app/site/users/components/group-list/group-list.component.html
+++ b/client/src/app/site/users/components/group-list/group-list.component.html
@@ -85,8 +85,8 @@
         <button type="button" mat-button (click)="cancelEditing()">
             <span translate>Cancel</span>
         </button>
-        <button *ngIf="selectedGroup" type="button" mat-icon-button color="warn" (click)="deleteSelectedGroup()">
-            <mat-icon>delete</mat-icon>
+        <button *ngIf="selectedGroup" [disabled]="!canDeleteGroup(selectedGroup)" type="button" mat-button color="warn" (click)="deleteSelectedGroup()">
+            <span translate>Delete</span>
         </button>
     </div>
 </ng-template>
diff --git a/client/src/app/site/users/components/group-list/group-list.component.ts b/client/src/app/site/users/components/group-list/group-list.component.ts
index 104d61024..47abe526c 100644
--- a/client/src/app/site/users/components/group-list/group-list.component.ts
+++ b/client/src/app/site/users/components/group-list/group-list.component.ts
@@ -149,6 +149,13 @@ export class GroupListComponent extends BaseViewComponent implements OnInit {
         this.selectedGroup = null;
     }
 
+    /**
+     * Prevent deleting group 1 and 2 (default and admin)
+     */
+    public canDeleteGroup(group: ViewGroup): boolean {
+        return group.id !== 1 && group.id !== 2;
+    }
+
     /**
      * Triggers when a permission was toggled
      * @param viewGroup
diff --git a/openslides/assignments/serializers.py b/openslides/assignments/serializers.py
index a89bef308..126d80776 100644
--- a/openslides/assignments/serializers.py
+++ b/openslides/assignments/serializers.py
@@ -76,7 +76,10 @@ class AssignmentOptionSerializer(ModelSerializer):
     def get_is_elected(self, obj):
         """
         Returns the election status of the candidate of this option.
+        If the candidate is None (e.g. deleted) the result is False.
         """
+        if not obj.candidate:
+            return False
         return obj.poll.assignment.is_elected(obj.candidate)