Java Language Support 1.46+ breaks agent loading

Java Language Support 1.46+ breaks agent loading

For years I have been using a jar file that only contains the manifest file for a agent. This allowed for a fast convenient workflow cause I can make changes to the agent and quickly test them without the need of rebuilding the jar file.

The last version this worked is 1.45.0, after this it's broken.

The output you get after 1.45.0 is:

  /usr/bin/env /Library/Java/JavaVirtualMachines/jdk-24.0.2.jdk/Contents/Home/bin/java -agentlib:jdwp=transport=dt_socket,server=n,suspe
nd=y,address=localhost:62572 @/var/folders/hz/57zbqcy11q30rv9_gbdlvckc0000gn/T/cp_2neoah6v6lbyb5srzf0syfujp.argfile imgui_2026_examples.Example 
Exception in thread "main" java.lang.ClassNotFoundException: imgui_2026.UI_Widget_Agent
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:490)
        at java.instrument/sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:488)
        at java.instrument/sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:556)
*** java.lang.instrument ASSERTION FAILED ***: "!errorOutstanding" with message Outstanding error when calling method in invokeJavaAgentMainMethod at open/src/java.instrument/share/native/libinstrument/JPLISAgent.c line: 627
*** java.lang.instrument ASSERTION FAILED ***: "success" with message invokeJavaAgentMainMethod failed at open/src/java.instrument/share/native/libinstrument/JPLISAgent.c line: 466
*** java.lang.instrument ASSERTION FAILED ***: "result" with message agent load/premain call failed at open/src/java.instrument/share/native/libinstrument/JPLISAgent.c line: 429
FATAL ERROR in native method: processing of -javaagent failed, processJavaStart failed
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.dylib+0x533e84]  jni_FatalError+0x7c
V  [libjvm.dylib+0x6a317c]  JvmtiExport::post_vm_initialized()+0x2cc
V  [libjvm.dylib+0x9dcc00]  Threads::create_vm(JavaVMInitArgs*, bool*)+0x7a4
V  [libjvm.dylib+0x552dc8]  JNI_CreateJavaVM+0x74
C  [libjli.dylib+0xa438]  JavaMain+0x100
C  [libjli.dylib+0xd72c]  ThreadJavaMain+0xc
C  [libsystem_pthread.dylib+0x6c0c]  _pthread_start+0x88
zsh: abort      /usr/bin/env    imgui_2026_examples.Example

To Reproduce

Steps to reproduce the behavior:

I made a repository with a really small setup to reproduce.

1. download https://github.com/clankill3r/java_language_support_bug
2. run with 1.45.0 👍
3. run with 1.46.0+ 👎

Expected behavior

Instead of a ClassNotFoundException it should be able to run.

Environment

• Operating System: OSX 15.6
• JDK version: jdk-24.0.2
• Visual Studio Code version: 1.121.0
• Java extension version: 1.45.0 / 1.46+

Start with the linked java_language_support_bug repository and reproduce the difference between Java Language Support 1.45.0 and 1.46.0+ using the provided environment. Compare the generated launch arguments or classpath and agent loading behavior; done when the manifest-only agent runs without ClassNotFoundException in the affected versions.