diff --git a/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/LiveServerMessage.kt b/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/LiveServerMessage.kt
index 5ab520af474..3e3e90636e5 100644
--- a/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/LiveServerMessage.kt
+++ b/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/LiveServerMessage.kt
@@ -183,7 +183,7 @@ internal object LiveServerMessageSerializer :
         LiveServerToolCallCancellation.InternalWrapper.serializer()
       else ->
         throw SerializationException(
-          "The given subclass of LiveServerMessage (${javaClass.simpleName}) is not supported in the serialization yet."
+          "Unknown LiveServerMessage response type. Keys found: ${jsonObject.keys}"
         )
     }
   }