diff --git a/libreplan-webapp/src/main/java/org/libreplan/web/planner/tabs/GanttDiagramBuilder.java b/libreplan-webapp/src/main/java/org/libreplan/web/planner/tabs/GanttDiagramBuilder.java
index 0b31077e7..2e2ad8a56 100644
--- a/libreplan-webapp/src/main/java/org/libreplan/web/planner/tabs/GanttDiagramBuilder.java
+++ b/libreplan-webapp/src/main/java/org/libreplan/web/planner/tabs/GanttDiagramBuilder.java
@@ -52,6 +52,9 @@ public class GanttDiagramBuilder {
         GanttDiagramGraph<TaskElement, DependencyWithVisibility> graph = createFor(
                 order, adapter);
         TaskSource taskSource = order.getTaskSource();
+        if (taskSource == null) {
+            return graph;
+        }
         graph.addTopLevel(taskSource.getTask());
         for (Dependency each : getAllDependencies(order)) {
             graph.addWithoutEnforcingConstraints(DependencyWithVisibility