--- old/src/java.base/share/classes/java/lang/UnknownError.java	2019-08-27 17:27:40.098324386 -0700
+++ new/src/java.base/share/classes/java/lang/UnknownError.java	2019-08-27 17:27:39.914324386 -0700
@@ -34,6 +34,7 @@
  */
 public
 class UnknownError extends VirtualMachineError {
+    @java.io.Serial
     private static final long serialVersionUID = 2524784860676771849L;
 
     /**