Index: /trunk/de.ugoe.cs.swe.bnftools.ebnf.ui/src/de/ugoe/cs/swe/bnftools/ui/quickfix/modifications/RemovePassthroughRuleModification.java
===================================================================
--- /trunk/de.ugoe.cs.swe.bnftools.ebnf.ui/src/de/ugoe/cs/swe/bnftools/ui/quickfix/modifications/RemovePassthroughRuleModification.java	(revision 53)
+++ /trunk/de.ugoe.cs.swe.bnftools.ebnf.ui/src/de/ugoe/cs/swe/bnftools/ui/quickfix/modifications/RemovePassthroughRuleModification.java	(revision 54)
@@ -48,4 +48,6 @@
 				resourceDescriptions, editor);
 
+		System.out.println(references);
+		
 		List<DeclarationReferencesPair> nodePairs = new ArrayList<DeclarationReferencesPair>();
 		nodePairs.add(new DeclarationReferencesPair((CompositeNode) declarationNode.getParserNode(), references));
Index: /trunk/de.ugoe.cs.swe.bnftools.ebnf.ui/src/de/ugoe/cs/swe/bnftools/utils/URIFragmentResolver.java
===================================================================
--- /trunk/de.ugoe.cs.swe.bnftools.ebnf.ui/src/de/ugoe/cs/swe/bnftools/utils/URIFragmentResolver.java	(revision 53)
+++ /trunk/de.ugoe.cs.swe.bnftools.ebnf.ui/src/de/ugoe/cs/swe/bnftools/utils/URIFragmentResolver.java	(revision 54)
@@ -18,4 +18,8 @@
 	public CompositeNode exec(XtextResource state) throws Exception {
 		EObject o = state.getEObject(uriFragment);
+		
+		if (o == null)
+			return null;
+		
 		NodeAdapter node = NodeUtil.getNodeAdapter(o);
 
Index: /trunk/de.ugoe.cs.swe.bnftools.ebnf.ui/src/de/ugoe/cs/swe/bnftools/utils/Utils.java
===================================================================
--- /trunk/de.ugoe.cs.swe.bnftools.ebnf.ui/src/de/ugoe/cs/swe/bnftools/utils/Utils.java	(revision 53)
+++ /trunk/de.ugoe.cs.swe.bnftools.ebnf.ui/src/de/ugoe/cs/swe/bnftools/utils/Utils.java	(revision 54)
@@ -106,8 +106,9 @@
 //TODO: dieser check ignoriert links zu anderen dateien wg. exception
 				if ((matchingReferenceDescription instanceof org.eclipse.xtext.resource.impl.DefaultReferenceDescription) || (matchingReferenceDescription instanceof ReferenceDescriptionImpl)){
-					CompositeNode node = editor.getDocument().readOnly(
-							new URIFragmentResolver(matchingReferenceDescription
-									.getSourceEObjectUri().fragment()));
-					references.add(node);
+					URIFragmentResolver uriFragmentResolver = new URIFragmentResolver(matchingReferenceDescription
+							.getSourceEObjectUri().fragment());
+					CompositeNode node = editor.getDocument().readOnly(uriFragmentResolver);
+					if (node != null)
+						references.add(node);
 				}
 			}