frontend/src/app/tasks/task-dashboard/task-dashboard.component.html

@@ -19,7 +19,8 @@
       <td mat-cell *matCellDef="let row">
         <mat-checkbox (click)="$event.stopPropagation()"
                       (change)="$event ? selection.toggle(row) : null"
-                      [checked]="selection.isSelected(row)">
+                      [checked]="selection.isSelected(row)"
+                      [disabled]="row.hasTaskSerie">
         </mat-checkbox>
       </td>
     </ng-container>

frontend/src/app/tasks/task-dashboard/task-dashboard.component.ts

@@ -48,7 +48,7 @@ export class TaskDashboardComponent implements OnChanges{
       return;
     }
 
-    this.selection.select(...this.datasource.data);
+    this.selection.select(...this.datasource.data.filter(task => !task.hasTaskSerie));
   }