diff --git a/org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/XtextGeneratorLanguage.xtend b/org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/XtextGeneratorLanguage.xtend
index 09c98c2c7..517459086 100644
--- a/org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/XtextGeneratorLanguage.xtend
+++ b/org.eclipse.xtext.xtext.generator/src/org/eclipse/xtext/xtext/generator/XtextGeneratorLanguage.xtend
@@ -202,10 +202,11 @@ class XtextGeneratorLanguage extends CompositeGeneratorFragment2 implements IXte
 
 				override add(Diagnostic diagnostic) {
 					if (diagnostic.severity == Diagnostic.ERROR) {
+						val grammarName = "Validation Error in " + grammar.name + ": "
 						if (diagnostic.exception == null)
-							throw new IllegalStateException(diagnostic.message)
+							throw new IllegalStateException(grammarName + diagnostic.message)
 						else
-							throw new IllegalStateException(diagnostic.message, diagnostic.exception)
+							throw new IllegalStateException(grammarName + diagnostic.message, diagnostic.exception)
 					}
 				}
 
diff --git a/org.eclipse.xtext.xtext.generator/xtend-gen/org/eclipse/xtext/xtext/generator/XtextGeneratorLanguage.java b/org.eclipse.xtext.xtext.generator/xtend-gen/org/eclipse/xtext/xtext/generator/XtextGeneratorLanguage.java
index fc60fbccc..737822661 100644
--- a/org.eclipse.xtext.xtext.generator/xtend-gen/org/eclipse/xtext/xtext/generator/XtextGeneratorLanguage.java
+++ b/org.eclipse.xtext.xtext.generator/xtend-gen/org/eclipse/xtext/xtext/generator/XtextGeneratorLanguage.java
@@ -331,15 +331,20 @@ public class XtextGeneratorLanguage extends CompositeGeneratorFragment2 implemen
           int _severity = diagnostic.getSeverity();
           boolean _equals = (_severity == Diagnostic.ERROR);
           if (_equals) {
+            String _name = grammar.getName();
+            String _plus = ("Validation Error in " + _name);
+            final String grammarName = (_plus + ": ");
             Throwable _exception = diagnostic.getException();
             boolean _equals_1 = Objects.equal(_exception, null);
             if (_equals_1) {
               String _message = diagnostic.getMessage();
-              throw new IllegalStateException(_message);
+              String _plus_1 = (grammarName + _message);
+              throw new IllegalStateException(_plus_1);
             } else {
               String _message_1 = diagnostic.getMessage();
+              String _plus_2 = (grammarName + _message_1);
               Throwable _exception_1 = diagnostic.getException();
-              throw new IllegalStateException(_message_1, _exception_1);
+              throw new IllegalStateException(_plus_2, _exception_1);
             }
           }
         }