diff --git a/javaExamples/Protocol.java b/javaExamples/Protocol.java
index 2dc565d..770f8cc 100644
--- a/javaExamples/Protocol.java
+++ b/javaExamples/Protocol.java
@@ -100,6 +100,7 @@ public enum Error {
         UNKNOWN_METHOD("010"),
         ILLEGAL_SYNTAX("011"),
         TIMEOUT("012"),
+        EXTENSION_NOT_EXSISTING("020"),
 
         // Server errors
         ILLEGAL_MOVE("120"),