For modals, response error messages is shown in the footer. For modals, Accept button is always on the right.

src/app/groups/group-item-edit/group-item-edit.component.html

@@ -39,15 +39,21 @@
     </mat-form-field>
   </mat-card-content>
   <mat-card-actions align="end">
-    <button mat-button
-            [disabled]="waitForResponse || formGroup.invalid"
-            (click)="add()">
-      <mat-icon>add</mat-icon>Add
-    </button>
     <button mat-button
             [disabled]="waitForResponse"
             (click)="cancel()">
       <mat-icon>cancel</mat-icon>Cancel
     </button>
+    <button mat-button
+            [disabled]="waitForResponse || formGroup.invalid"
+            (click)="add()">
+      <mat-icon>add</mat-icon>Add
+    </button>
   </mat-card-actions>
+
+  @if (responseError) {
+  <mat-card-footer>
+    <small class="error below">{{responseError}}</small>
+  </mat-card-footer>
+  }
 </mat-card>