diff --git a/debug/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/TreeModelContentProvider.java b/debug/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/TreeModelContentProvider.java
index 075bad86e78..04a1569aeb4 100644
--- a/debug/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/TreeModelContentProvider.java
+++ b/debug/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/viewers/model/TreeModelContentProvider.java
@@ -1185,9 +1185,10 @@ void doUpdateElement(TreePath parentPath, int modelIndex) {
 		Assert.isTrue( getViewer().getDisplay().getThread() == Thread.currentThread() );
 
 		Object parent = getElement(parentPath);
+		Object viewerInput = getViewer().getInput();
 		IElementContentProvider contentAdapter = ViewerAdapterService.getContentProvider(parent);
-		if (contentAdapter != null) {
-			ChildrenUpdate request = new ChildrenUpdate(this, getViewer().getInput(), parentPath, parent, modelIndex, contentAdapter);
+		if (viewerInput != null && contentAdapter != null) {
+			ChildrenUpdate request = new ChildrenUpdate(this, viewerInput, parentPath, parent, modelIndex, contentAdapter);
 			schedule(request);
 		}
 	}