The following test fails when it is run with --enable-preview:

jdk/jfr/event/runtime/TestSyncOnValueBasedClassEvent.java

Here's a snippet from the log file:

#section:main
----------messages:(8/546)----------
command: main -XX:+UnlockDiagnosticVMOptions -XX:DiagnoseSyncOnValueBasedClasses=2 jdk.jfr.event.runtime.TestSyncOnValueBasedClassEvent
reason: User specified action: run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:DiagnoseSyncOnValueBasedClasses=2 jdk.jfr.event.runtime.TestSyncOnValueBasedClassEvent
started: Thu Jan 08 00:18:22.342 GMT 2026
Mode: othervm [/othervm specified]
Additional options from @modules: --add-modules jdk.jfr,java.management
Process id: 49558
finished: Thu Jan 08 00:18:24.062 GMT 2026
elapsed time (seconds): 1.72
----------configuration:(3/51)----------
Boot Layer
  add modules: jdk.jfr java.management

----------System.out:(0/0)----------
----------System.err:(11/817)----------
java.lang.IdentityException: Cannot synchronize on an instance of value class java.lang.Character
at jdk.jfr.event.runtime.TestSyncOnValueBasedClassEvent.main(TestSyncOnValueBasedClassEvent.java:70)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
at java.base/java.lang.Thread.run(Thread.java:1516)

JavaTest Message: Test threw exception: java.lang.IdentityException: Cannot synchronize on an instance of value class java.lang.Character
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.IdentityException: Cannot synchronize on an instance of value class java.lang.Character
----------rerun:(44/8168)*----------

In this particular case, the test task is invoked with the
--enable-preview option and this results in the test execution
command containing this snippet:

        -Dtest.java.opts=--enable-preview \\