diff --git a/core/trino-main/src/main/java/io/trino/execution/StageState.java b/core/trino-main/src/main/java/io/trino/execution/StageState.java
index b66af5b439ce2..27013ba787a01 100644
--- a/core/trino-main/src/main/java/io/trino/execution/StageState.java
+++ b/core/trino-main/src/main/java/io/trino/execution/StageState.java
@@ -116,6 +116,6 @@ public boolean canScheduleMoreTasks()
                 // completing successfully when it should fail..
                 return true;
         }
-        return true;
+        throw new IllegalStateException("Unhandled state: " + this);
     }
 }