diff --git a/gluten-core/src/main/scala/org/apache/spark/sql/execution/GlutenFallbackReporter.scala b/gluten-core/src/main/scala/org/apache/spark/sql/execution/GlutenFallbackReporter.scala
index 00b0248aee77..721a30eb4f40 100644
--- a/gluten-core/src/main/scala/org/apache/spark/sql/execution/GlutenFallbackReporter.scala
+++ b/gluten-core/src/main/scala/org/apache/spark/sql/execution/GlutenFallbackReporter.scala
@@ -89,6 +89,7 @@ case class GlutenFallbackReporter(glutenConfig: GlutenConfig, spark: SparkSessio
                 logicalPlan.setTagValue(FALLBACK_REASON_TAG, newReason)
             }
           case TRANSFORM_UNSUPPORTED(_, _) =>
+            logFallbackReason(validationLogLevel, p.nodeName, "unknown reason")
           case _ =>
             throw new IllegalStateException("Unreachable code")
         }