diff --git a/src/main/java/org/onosproject/aaa/StateMachineInvalidTransitionException.java b/src/main/java/org/onosproject/aaa/StateMachineInvalidTransitionException.java
new file mode 100644
index 0000000..9f41a34
--- /dev/null
+++ b/src/main/java/org/onosproject/aaa/StateMachineInvalidTransitionException.java
@@ -0,0 +1,27 @@
+/*
+ *
+ * Copyright 2015 AT&T Foundry
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package org.onosproject.aaa;
+
+/**
+ * Exception raised when the transition from one state to another is invalid.
+ */
+class StateMachineInvalidTransitionException extends StateMachineException {
+    public StateMachineInvalidTransitionException(String message) {
+        super(message);
+    }
+}