The following test fails in the Valhalla CI when --enable-preview is used:

vmTestbase/nsk/jdi/ModificationWatchpointEvent/valueToBe/valuetobe001/TestDescription.java

Here's a snippet from the log file:

#section:driver
----------messages:(10/1250)----------
command: driver nsk.jdi.ModificationWatchpointEvent.valueToBe.valuetobe001 -verbose -arch=linux-aarch64 -waittime=5 -debugee.vmkind=java -transport.address=dynamic -debugee.vmkeys="-XX:MaxRAMPercentage=6.25 -Dtest.boot.jdk=/opt/mach5/mesos/work_dir/jib-master/install/jdk/25/37/bundles/linux-aarch64/jdk-25_linux-aarch64_bin.tar.gz/jdk-25 -Djava.io.tmpdir=/opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S11675/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/b4347805-9d4c-409e-97f1-830888c92ab0/runs/a13c444d-fbea-4457-b178-2afb185ac961/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jdi/tmp --enable-preview"
reason: User specified action: run driver nsk.jdi.ModificationWatchpointEvent.valueToBe.valuetobe001 -verbose -arch=${os.family}-${os.simpleArch} -waittime=5 -debugee.vmkind=java -transport.address=dynamic -debugee.vmkeys="${test.vm.opts} ${test.java.opts}"
started: Thu Jan 08 14:09:55.740 UTC 2026
Mode: agentvm
Agent id: 5
Process id: 1311511
Additional exports to unnamed modules from @modules: java.base/jdk.internal.misc
Additional opens to unnamed modules from @modules: java.base/jdk.internal.misc
finished: Thu Jan 08 14:09:57.449 UTC 2026
elapsed time (seconds): 1.709
----------configuration:(18/2760)----------

<snip>

----------System.out:(403/30412)*----------
[14:9:55.891] Connecting to debuggee
[14:9:55.892] binder> VirtualMachineManager: version 27.0
[14:9:55.893] binder> Finding connector: default
[14:9:55.893] binder> LaunchingConnector:
[14:9:55.893] binder> name: com.sun.jdi.CommandLineLaunch
[14:9:55.893] binder> description: Launches target using Sun Java VM command line and attaches to it
[14:9:55.893] binder> transport: com.sun.tools.jdi.SunCommandLineLauncher$2@1f0272db
[14:9:55.902] binder> Connector arguments:
[14:9:55.903] binder> main=nsk.jdi.ModificationWatchpointEvent.valueToBe.valuetobe001a \u0000-verbose\u0000 \u0000-arch=linux-aarch64\u0000 \u0000-waittime=5\u0000 \u0000-debugee.vmkind=java\u0000 \u0000-transport.address=dynamic\u0000 \u0000-debugee.vmkeys="-XX:MaxRAMPercentage=6.25 -Dtest.boot.jdk=/opt/mach5/mesos/work_dir/jib-master/install/jdk/25/37/bundles/linux-aarch64/jdk-25_linux-aarch64_bin.tar.gz/jdk-25 -Djava.io.tmpdir=/opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S11675/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/b4347805-9d4c-409e-97f1-830888c92ab0/runs/a13c444d-fbea-4457-b178-2afb185ac961/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jdi/tmp --enable-preview"\u0000 \u0000-pipe.port=57263\u0000
[14:9:55.903] binder> includevirtualthreads=n
[14:9:55.903] binder> quote=\u0000
[14:9:55.903] binder> home=/opt/mach5/mesos/work_dir/jib-master/install/jdk-27-valhalla+1-20/linux-aarch64-debug.jdk/jdk-27/fastdebug
[14:9:55.903] binder> vmexec=java
[14:9:55.903] binder> suspend=true
[14:9:55.903] binder> options=-XX:MaxRAMPercentage=6.25 -Dtest.boot.jdk=/opt/mach5/mesos/work_dir/jib-master/install/jdk/25/37/bundles/linux-aarch64/jdk-25_linux-aarch64_bin.tar.gz/jdk-25 -Djava.io.tmpdir=/opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S11675/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/b4347805-9d4c-409e-97f1-830888c92ab0/runs/a13c444d-fbea-4457-b178-2afb185ac961/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jdi/tmp --enable-preview -classpath \u0000/opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S11675/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/b4347805-9d4c-409e-97f1-830888c92ab0/runs/a13c444d-fbea-4457-b178-2afb185ac961/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jdi/classes/3/vmTestbase/nsk/jdi/ModificationWatchpointEvent/valueToBe/valuetobe001/TestDescription.d:/opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S11675/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/b4347805-9d4c-409e-97f1-830888c92ab0/runs/a13c444d-fbea-4457-b178-2afb185ac961/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jdi/classes/3/vmTestbase/nsk/jdi/ModificationWatchpointEvent/valueToBe/valuetobe001/TestDescription.d/vmTestbase:/opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S11675/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/b4347805-9d4c-409e-97f1-830888c92ab0/runs/a13c444d-fbea-4457-b178-2afb185ac961/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jdi/classes/3/vmTestbase/nsk/jdi/ModificationWatchpointEvent/valueToBe/valuetobe001/TestDescription.d/test/lib\u0000
[14:9:55.903] binder> Launching debugee
[14:9:56.80] binder> Waiting for VM initialized
[14:9:56.80] Initial VMStartEvent received: VMStartEvent in thread main
[14:9:56.80] Resuming debuggee
[14:9:56.136] Waiting for command: ready
[14:9:56.705] Creating requests for WatchpointEvent
[14:9:56.708] ModificationWatchpointRequest for field z0 created
[14:9:56.708] ModificationWatchpointRequest for field z1 created
[14:9:56.708] ModificationWatchpointRequest for field z2 created

<snip>

[14:9:56.864] ModificationWatchpointEvent received for lV2
[14:9:56.865] lV2 is assigned to instance of long[][1] (id=892)
[14:9:56.868] ModificationWatchpointEvent received for X0
[14:9:56.868] X0 is assigned to instance of nsk.jdi.ModificationWatchpointEvent.valueToBe.valuetobe001aCheckedClass$Class(id=894)
[14:9:56.870] ModificationWatchpointEvent received for X1
[14:9:56.871] X1 is assigned to instance of nsk.jdi.ModificationWatchpointEvent.valueToBe.valuetobe001aCheckedClass$Class[1] (id=896)
[14:9:56.873] ModificationWatchpointEvent received for X2
[14:9:56.874] X2 is assigned to instance of nsk.jdi.ModificationWatchpointEvent.valueToBe.valuetobe001aCheckedClass$Class[][1] (id=899)
[14:9:56.876] ModificationWatchpointEvent received for Z0
[14:9:56.877] # ERROR: FAILURE 4: method valueToBe() returns incorrect equal value for Z0
[14:9:56.877] # ERROR: valuetoBe(): instance of java.lang.Boolean(id=902) ; valueCurrent(): instance of java.lang.Boolean(id=902)
The following stacktrace is for failure analysis.
nsk.share.TestFailure: FAILURE 4: method valueToBe() returns incorrect equal value for Z0 valuetoBe(): instance of java.lang.Boolean(id=902) ; valueCurrent(): instance of java.lang.Boolean(id=902)
at nsk.share.Log.logExceptionForFailureAnalysis(Log.java:309)
at nsk.share.Log.complain(Log.java:280)
at nsk.jdi.ModificationWatchpointEvent.valueToBe.valuetobe001$1EventHandler.run(valuetobe001.java:191)

There are currently 42 of these failures in the Valhalla CI on
all of the Mach5 platforms. All of the failing test tasks have
"*enable-preview*" in the name.