Write Exception like "Unsupported class file major version 69" to System.out.err

[chrisrueger]

Yesterday I was trying to run our app with JDK25 (instead of JDK21) but I noticed that no logging was was working.
We are using Slf4j (2.x), Logback, Aries Spifly (org.apache.aries.spifly:org.apache.aries.spifly.dynamic.bundle:1.3.7 for the slf4j 2.x ServiceLocator stuff) and we upgraded to org.eclipse.platform:org.eclipse.osgi:3.23.200 to fix the Unsafe warnings.

I only saw this on the console:

Okt. 22, 2025 7:14:18 AM org.apache.aries.spifly.BaseActivator log
INFORMATION: Registered provider ch.qos.logback.classic.servlet.LogbackServletContainerInitializer of service jakarta.servlet.ServletContainerInitializer in bundle ch.qos.logback.classic
Okt. 22, 2025 7:14:18 AM org.apache.aries.spifly.BaseActivator log
INFORMATION: Registered provider ch.qos.logback.classic.spi.LogbackServiceProvider of service org.slf4j.spi.SLF4JServiceProvider in bundle ch.qos.logback.classic
Okt. 22, 2025 7:14:18 AM org.apache.aries.spifly.BaseActivator log
INFORMATION: Registered provider org.eclipse.jetty.http.Http1FieldPreEncoder of service org.eclipse.jetty.http.HttpFieldPreEncoder in bundle org.apache.felix.http.jetty
Okt. 22, 2025 7:14:18 AM org.apache.aries.spifly.BaseActivator log
INFORMATION: Registered provider org.eclipse.jetty.http2.hpack.HpackFieldPreEncoder of service org.eclipse.jetty.http.HttpFieldPreEncoder in bundle org.apache.felix.http.jetty
SLF4J(W): No SLF4J providers were found.
SLF4J(W): Defaulting to no-operation (NOP) logger implementation
SLF4J(W): See https://www.slf4j.org/codes.html#noProviders for further details.
Okt. 22, 2025 7:14:19 AM org.apache.aries.spifly.BaseActivator log

So spifly seems to register the SLF4JServiceProvider but it could not be found.

After endless debugging attempts I finally arrived in this catch-block:

equinox/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/weaving/WeavingHookConfigurator.java

Lines 86 to 95 in dbeca31

	} catch (Throwable t) {
	ServiceRegistration<?> errorHook = wovenClass.getErrorHook();
	Bundle errorBundle = errorHook != null ? errorHook.getReference().getBundle()
	: manager.getGeneration().getRevision().getBundle();
	container.getEventPublisher().publishFrameworkEvent(FrameworkEvent.ERROR, errorBundle, t);
	// fail hard with a class loading error
	ClassFormatError error = new ClassFormatError("Unexpected error from weaving hook."); //$NON-NLS-1$
	error.initCause(t);
	throw error;
	} finally {

for wovenClass org.apache.logging.log4j.util.Activator
with the Error: java.lang.IllegalArgumentException: Unsupported class file major version 69

After turning on Equinox debug logging
I found out via Equinox Debug logging org.eclipse.osgi/debug/loader=true (see how to enable )

I got this

BundleLoader[org.objectweb.asm.tree_9.7.1] found local class org.objectweb.asm.tree.LdcInsnNode 0ms
BundleLoader[org.objectweb.asm.tree_9.7.1].findClass(org.objectweb.asm.tree.UnsupportedClassVersionException)
BundleLoader[org.objectweb.asm.tree_9.7.1].findLocalClass(org.objectweb.asm.tree.UnsupportedClassVersionException)
ModuleClassLoader[org.objectweb.asm.tree_9.7.1 - /Users/me/.m2/repository/org/ow2/asm/asm-tree/9.7.1/asm-tree-9.7.1.jar].findClassImpl(org.objectweb.asm.tree.UnsupportedClassVersionException)
  read 441 bytes from /Users/me/.m2/repository/org/ow2/asm/asm-tree/9.7.1/asm-tree-9.7.1.jar!/org/objectweb/asm/tree/UnsupportedClassVersionException.class

That told me that I had to update the asm libs from 9.7.1 to 9.9:

org.ow2.asm:asm:9.9
org.ow2.asm:asm-commons:9.9
org.ow2.asm:asm-util:9.9
org.ow2.asm:asm-tree:9.9
org.ow2.asm:asm-analysis:9.9

After that the exception was gone.

My question is:
Could we log this exception maybe to System.out.err so that it gets noticed easier? So that it prints to the console similar to the spifly and slf4j log earlier?

[tjwatson]

Could we log this exception maybe to System.out.err so that it gets noticed easier?

The thing I am not understanding is why this is not logging the exception for you:

equinox/bundles/org.eclipse.osgi/container/src/org/eclipse/osgi/internal/weaving/WeavingHookConfigurator.java

Line 90 in dbeca31

container.getEventPublisher().publishFrameworkEvent(FrameworkEvent.ERROR, errorBundle, t);

That should have been logged to the eclipse/equinox log file as well as the OSGi Logger.

[tjwatson]

We try to avoid sending stuff to System out/err. There are some rare places we do, but that is usually in very lowlevel bootstrap kind of code where not even the eclipse logger is available.

[chrisrueger]

The thing I am not understanding is why this is not logging the exception for you:
That should have been logged to the eclipse/equinox log file as well as the OSGi Logger.

That is a good question. Maybe because I just found out about how to configure Equinox debug logging during the process yesterday (via the debug.options file and setting osgi.debug=debug.options logging org.eclipse.osgi/debug/loader=true). I did have that before. So not sure where I would normally find this equinox log file if I haven't configured it.

We try to avoid sending stuff to System out/err. There are some rare places we do, but that is usually in very lowlevel bootstrap kind of code where not even the eclipse logger is available.

Understandable. But since I was basically wrestling with non-working logging, at least for me that would have been a place where I would have seen it. It was completely invisible to me.

What could I provide you to see what kind of logging I had?

[tjwatson]

Understandable. But since I was basically wrestling with non-working logging, at least for me that would have been a place where I would have seen it. It was completely invisible to me.

By default Equinox should have written the framework ERROR to a log file also from here unless you disabled it with the property eclipse.log.enabled=false which gets read here

Also note that if you prefer the built-in equinox logger to go to System.out also then you can set the framework/system property eclipse.consoleLog=true

[chrisrueger]

Thanks I will experiment with that. (I had none of the properties set)

[chrisrueger]

Thanks 👍
eclipse.consoleLog=true was exactly what I needed. Then I get the error stacktrace in the bad case, but no logging output after I fixed it. I will basically keep it eclipse.consoleLog=true from now on...at least in local development mode (e.g. via bnd conditional variable or different .bndrun for local debugging)

Okt. 22, 2025 4:35:01 PM org.apache.aries.spifly.BaseActivator log
INFORMATION: Registered provider ch.qos.logback.classic.servlet.LogbackServletContainerInitializer of service jakarta.servlet.ServletContainerInitializer in bundle ch.qos.logback.classic
Okt. 22, 2025 4:35:01 PM org.apache.aries.spifly.BaseActivator log
INFORMATION: Registered provider ch.qos.logback.classic.spi.LogbackServiceProvider of service org.slf4j.spi.SLF4JServiceProvider in bundle ch.qos.logback.classic
!SESSION 2025-10-22 16:35:01.108 -----------------------------------------------
eclipse.buildId=unknown
java.version=25
java.vendor=Eclipse Adoptium
BootLoader constants: OS=macosx, ARCH=aarch64, WS=cocoa, NL=de_DE

!ENTRY org.apache.aries.spifly.dynamic.bundle 4 0 2025-10-22 16:35:01.117
!MESSAGE FrameworkEvent ERROR
!STACK 0
java.lang.IllegalArgumentException: Unsupported class file major version 69
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:200)
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:180)
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:166)
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:288)
	at org.apache.aries.spifly.dynamic.OSGiFriendlyClassWriter.getCommonSuperClass(OSGiFriendlyClassWriter.java:84)
	at org.objectweb.asm.SymbolTable.addMergedType(SymbolTable.java:1286)
	at org.objectweb.asm.Frame.merge(Frame.java:1311)
	at org.objectweb.asm.Frame.merge(Frame.java:1208)
	at org.objectweb.asm.MethodWriter.computeAllFrames(MethodWriter.java:1612)
	at org.objectweb.asm.MethodWriter.visitMaxs(MethodWriter.java:1548)
	at org.objectweb.asm.MethodVisitor.visitMaxs(MethodVisitor.java:787)
	at org.objectweb.asm.commons.LocalVariablesSorter.visitMaxs(LocalVariablesSorter.java:147)
	at org.objectweb.asm.tree.MethodNode.accept(MethodNode.java:767)
	at org.objectweb.asm.commons.JSRInlinerAdapter.visitEnd(JSRInlinerAdapter.java:159)
	at org.objectweb.asm.ClassReader.readMethod(ClassReader.java:1516)
	at org.objectweb.asm.ClassReader.accept(ClassReader.java:745)
	at org.objectweb.asm.ClassReader.accept(ClassReader.java:425)
	at org.apache.aries.spifly.dynamic.ClientWeavingHook.weave(ClientWeavingHook.java:60)
	at org.eclipse.osgi.internal.weaving.WovenClassImpl.call(WovenClassImpl.java:194)
	at org.eclipse.osgi.internal.weaving.WovenClassImpl.call(WovenClassImpl.java:1)
	at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.notifyHookPrivileged(ServiceRegistry.java:1442)
	at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.notifyHooksPrivileged(ServiceRegistry.java:1415)
	at org.eclipse.osgi.internal.weaving.WovenClassImpl.callHooks(WovenClassImpl.java:269)
	at org.eclipse.osgi.internal.weaving.WeavingHookConfigurator.processClass(WeavingHookConfigurator.java:85)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.processClass(ClasspathManager.java:798)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.defineClass(ClasspathManager.java:768)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findClassImpl(ClasspathManager.java:695)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClassImpl(ClasspathManager.java:659)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClassImpl(ClasspathManager.java:639)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClass(ClasspathManager.java:618)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.findLocalClass(ModuleClassLoader.java:353)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:417)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass0(BundleLoader.java:525)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:438)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.loadBundleActivator(BundleContextImpl.java:807)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.start(BundleContextImpl.java:753)
	at org.eclipse.osgi.internal.framework.EquinoxBundle.startWorker0(EquinoxBundle.java:1066)
	at org.eclipse.osgi.internal.framework.EquinoxBundle$EquinoxModule.startWorker(EquinoxBundle.java:394)
	at org.eclipse.osgi.container.Module.doStart(Module.java:643)
	at org.eclipse.osgi.container.Module.start(Module.java:500)
	at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:528)
	at org.eclipse.osgi.internal.hooks.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:122)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClass(ClasspathManager.java:622)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.findLocalClass(ModuleClassLoader.java:353)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:417)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass0(BundleLoader.java:525)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:438)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:195)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:490)
	at org.eclipse.osgi.internal.framework.EquinoxBundle.loadClass(EquinoxBundle.java:652)
	at org.apache.aries.spifly.ProviderBundleTrackerCustomizer.addingBundle(ProviderBundleTrackerCustomizer.java:143)
	at org.apache.aries.spifly.ProviderBundleTrackerCustomizer.addingBundle(ProviderBundleTrackerCustomizer.java:64)
	at org.osgi.util.tracker.BundleTracker$Tracked.customizerAdding(BundleTracker.java:477)
	at org.osgi.util.tracker.BundleTracker$Tracked.customizerAdding(BundleTracker.java:1)
	at org.osgi.util.tracker.AbstractTracked.trackAdding(AbstractTracked.java:257)
	at org.osgi.util.tracker.AbstractTracked.track(AbstractTracked.java:230)
	at org.osgi.util.tracker.BundleTracker$Tracked.bundleChanged(BundleTracker.java:452)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.dispatchEvent(BundleContextImpl.java:975)
	at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
	at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:151)
	at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEventPrivileged(EquinoxEventPublisher.java:237)
	at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEvent(EquinoxEventPublisher.java:136)
	at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEvent(EquinoxEventPublisher.java:128)
	at org.eclipse.osgi.internal.framework.EquinoxContainerAdaptor.publishModuleEvent(EquinoxContainerAdaptor.java:232)
	at org.eclipse.osgi.container.Module.publishEvent(Module.java:534)
	at org.eclipse.osgi.container.Module.start(Module.java:518)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel$2.run(ModuleContainer.java:2110)
	at org.eclipse.osgi.internal.framework.EquinoxContainerAdaptor$1$1.execute(EquinoxContainerAdaptor.java:146)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.incStartLevel(ModuleContainer.java:2101)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.incStartLevel(ModuleContainer.java:2041)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.doContainerStartLevel(ModuleContainer.java:2003)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.dispatchEvent(ModuleContainer.java:1915)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.dispatchEvent(ModuleContainer.java:1)
	at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
	at org.eclipse.osgi.framework.eventmgr.EventManager$EventThread.run(EventManager.java:341)

!ENTRY org.eclipse.osgi 4 0 2025-10-22 16:35:01.120
!MESSAGE An error occurred while automatically activating bundle org.apache.logging.log4j.api (13).
!STACK 0
org.osgi.framework.BundleException: Error starting module. osgi.identity; type="osgi.bundle"; version:Version="2.25.2"; osgi.identity="org.apache.logging.log4j.api" [id=13]
	at org.eclipse.osgi.container.Module.doStart(Module.java:652)
	at org.eclipse.osgi.container.Module.start(Module.java:500)
	at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:528)
	at org.eclipse.osgi.internal.hooks.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:122)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClass(ClasspathManager.java:622)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.findLocalClass(ModuleClassLoader.java:353)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:417)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass0(BundleLoader.java:525)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:438)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:195)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:490)
	at org.eclipse.osgi.internal.framework.EquinoxBundle.loadClass(EquinoxBundle.java:652)
	at org.apache.aries.spifly.ProviderBundleTrackerCustomizer.addingBundle(ProviderBundleTrackerCustomizer.java:143)
	at org.apache.aries.spifly.ProviderBundleTrackerCustomizer.addingBundle(ProviderBundleTrackerCustomizer.java:64)
	at org.osgi.util.tracker.BundleTracker$Tracked.customizerAdding(BundleTracker.java:477)
	at org.osgi.util.tracker.BundleTracker$Tracked.customizerAdding(BundleTracker.java:1)
	at org.osgi.util.tracker.AbstractTracked.trackAdding(AbstractTracked.java:257)
	at org.osgi.util.tracker.AbstractTracked.track(AbstractTracked.java:230)
	at org.osgi.util.tracker.BundleTracker$Tracked.bundleChanged(BundleTracker.java:452)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.dispatchEvent(BundleContextImpl.java:975)
	at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
	at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:151)
	at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEventPrivileged(EquinoxEventPublisher.java:237)
	at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEvent(EquinoxEventPublisher.java:136)
	at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEvent(EquinoxEventPublisher.java:128)
	at org.eclipse.osgi.internal.framework.EquinoxContainerAdaptor.publishModuleEvent(EquinoxContainerAdaptor.java:232)
	at org.eclipse.osgi.container.Module.publishEvent(Module.java:534)
	at org.eclipse.osgi.container.Module.start(Module.java:518)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel$2.run(ModuleContainer.java:2110)
	at org.eclipse.osgi.internal.framework.EquinoxContainerAdaptor$1$1.execute(EquinoxContainerAdaptor.java:146)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.incStartLevel(ModuleContainer.java:2101)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.incStartLevel(ModuleContainer.java:2041)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.doContainerStartLevel(ModuleContainer.java:2003)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.dispatchEvent(ModuleContainer.java:1915)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.dispatchEvent(ModuleContainer.java:1)
	at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
	at org.eclipse.osgi.framework.eventmgr.EventManager$EventThread.run(EventManager.java:341)
Caused by: java.lang.ClassFormatError: Unexpected error from weaving hook.
	at org.eclipse.osgi.internal.weaving.WeavingHookConfigurator.processClass(WeavingHookConfigurator.java:92)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.processClass(ClasspathManager.java:798)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.defineClass(ClasspathManager.java:768)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findClassImpl(ClasspathManager.java:695)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClassImpl(ClasspathManager.java:659)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClassImpl(ClasspathManager.java:639)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClass(ClasspathManager.java:618)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.findLocalClass(ModuleClassLoader.java:353)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:417)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass0(BundleLoader.java:525)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:438)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.loadBundleActivator(BundleContextImpl.java:807)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.start(BundleContextImpl.java:753)
	at org.eclipse.osgi.internal.framework.EquinoxBundle.startWorker0(EquinoxBundle.java:1066)
	at org.eclipse.osgi.internal.framework.EquinoxBundle$EquinoxModule.startWorker(EquinoxBundle.java:394)
	at org.eclipse.osgi.container.Module.doStart(Module.java:643)
	... 36 more
Caused by: java.lang.IllegalArgumentException: Unsupported class file major version 69
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:200)
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:180)
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:166)
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:288)
	at org.apache.aries.spifly.dynamic.OSGiFriendlyClassWriter.getCommonSuperClass(OSGiFriendlyClassWriter.java:84)
	at org.objectweb.asm.SymbolTable.addMergedType(SymbolTable.java:1286)
	at org.objectweb.asm.Frame.merge(Frame.java:1311)
	at org.objectweb.asm.Frame.merge(Frame.java:1208)
	at org.objectweb.asm.MethodWriter.computeAllFrames(MethodWriter.java:1612)
	at org.objectweb.asm.MethodWriter.visitMaxs(MethodWriter.java:1548)
	at org.objectweb.asm.MethodVisitor.visitMaxs(MethodVisitor.java:787)
	at org.objectweb.asm.commons.LocalVariablesSorter.visitMaxs(LocalVariablesSorter.java:147)
	at org.objectweb.asm.tree.MethodNode.accept(MethodNode.java:767)
	at org.objectweb.asm.commons.JSRInlinerAdapter.visitEnd(JSRInlinerAdapter.java:159)
	at org.objectweb.asm.ClassReader.readMethod(ClassReader.java:1516)
	at org.objectweb.asm.ClassReader.accept(ClassReader.java:745)
	at org.objectweb.asm.ClassReader.accept(ClassReader.java:425)
	at org.apache.aries.spifly.dynamic.ClientWeavingHook.weave(ClientWeavingHook.java:60)
	at org.eclipse.osgi.internal.weaving.WovenClassImpl.call(WovenClassImpl.java:194)
	at org.eclipse.osgi.internal.weaving.WovenClassImpl.call(WovenClassImpl.java:1)
	at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.notifyHookPrivileged(ServiceRegistry.java:1442)
	at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.notifyHooksPrivileged(ServiceRegistry.java:1415)
	at org.eclipse.osgi.internal.weaving.WovenClassImpl.callHooks(WovenClassImpl.java:269)
	at org.eclipse.osgi.internal.weaving.WeavingHookConfigurator.processClass(WeavingHookConfigurator.java:85)
	... 51 more
Root exception:
java.lang.ClassFormatError: Unexpected error from weaving hook.
	at org.eclipse.osgi.internal.weaving.WeavingHookConfigurator.processClass(WeavingHookConfigurator.java:92)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.processClass(ClasspathManager.java:798)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.defineClass(ClasspathManager.java:768)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findClassImpl(ClasspathManager.java:695)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClassImpl(ClasspathManager.java:659)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClassImpl(ClasspathManager.java:639)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClass(ClasspathManager.java:618)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.findLocalClass(ModuleClassLoader.java:353)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:417)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass0(BundleLoader.java:525)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:438)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.loadBundleActivator(BundleContextImpl.java:807)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.start(BundleContextImpl.java:753)
	at org.eclipse.osgi.internal.framework.EquinoxBundle.startWorker0(EquinoxBundle.java:1066)
	at org.eclipse.osgi.internal.framework.EquinoxBundle$EquinoxModule.startWorker(EquinoxBundle.java:394)
	at org.eclipse.osgi.container.Module.doStart(Module.java:643)
	at org.eclipse.osgi.container.Module.start(Module.java:500)
	at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:528)
	at org.eclipse.osgi.internal.hooks.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:122)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClass(ClasspathManager.java:622)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.findLocalClass(ModuleClassLoader.java:353)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:417)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass0(BundleLoader.java:525)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:438)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:195)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:490)
	at org.eclipse.osgi.internal.framework.EquinoxBundle.loadClass(EquinoxBundle.java:652)
	at org.apache.aries.spifly.ProviderBundleTrackerCustomizer.addingBundle(ProviderBundleTrackerCustomizer.java:143)
	at org.apache.aries.spifly.ProviderBundleTrackerCustomizer.addingBundle(ProviderBundleTrackerCustomizer.java:64)
	at org.osgi.util.tracker.BundleTracker$Tracked.customizerAdding(BundleTracker.java:477)
	at org.osgi.util.tracker.BundleTracker$Tracked.customizerAdding(BundleTracker.java:1)
	at org.osgi.util.tracker.AbstractTracked.trackAdding(AbstractTracked.java:257)
	at org.osgi.util.tracker.AbstractTracked.track(AbstractTracked.java:230)
	at org.osgi.util.tracker.BundleTracker$Tracked.bundleChanged(BundleTracker.java:452)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.dispatchEvent(BundleContextImpl.java:975)
	at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
	at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:151)
	at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEventPrivileged(EquinoxEventPublisher.java:237)
	at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEvent(EquinoxEventPublisher.java:136)
	at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEvent(EquinoxEventPublisher.java:128)
	at org.eclipse.osgi.internal.framework.EquinoxContainerAdaptor.publishModuleEvent(EquinoxContainerAdaptor.java:232)
	at org.eclipse.osgi.container.Module.publishEvent(Module.java:534)
	at org.eclipse.osgi.container.Module.start(Module.java:518)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel$2.run(ModuleContainer.java:2110)
	at org.eclipse.osgi.internal.framework.EquinoxContainerAdaptor$1$1.execute(EquinoxContainerAdaptor.java:146)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.incStartLevel(ModuleContainer.java:2101)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.incStartLevel(ModuleContainer.java:2041)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.doContainerStartLevel(ModuleContainer.java:2003)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.dispatchEvent(ModuleContainer.java:1915)
	at org.eclipse.osgi.container.ModuleContainer$ContainerStartLevel.dispatchEvent(ModuleContainer.java:1)
	at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
	at org.eclipse.osgi.framework.eventmgr.EventManager$EventThread.run(EventManager.java:341)
Caused by: java.lang.IllegalArgumentException: Unsupported class file major version 69
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:200)
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:180)
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:166)
	at org.objectweb.asm.ClassReader.<init>(ClassReader.java:288)
	at org.apache.aries.spifly.dynamic.OSGiFriendlyClassWriter.getCommonSuperClass(OSGiFriendlyClassWriter.java:84)
	at org.objectweb.asm.SymbolTable.addMergedType(SymbolTable.java:1286)
	at org.objectweb.asm.Frame.merge(Frame.java:1311)
	at org.objectweb.asm.Frame.merge(Frame.java:1208)
	at org.objectweb.asm.MethodWriter.computeAllFrames(MethodWriter.java:1612)
	at org.objectweb.asm.MethodWriter.visitMaxs(MethodWriter.java:1548)
	at org.objectweb.asm.MethodVisitor.visitMaxs(MethodVisitor.java:787)
	at org.objectweb.asm.commons.LocalVariablesSorter.visitMaxs(LocalVariablesSorter.java:147)
	at org.objectweb.asm.tree.MethodNode.accept(MethodNode.java:767)
	at org.objectweb.asm.commons.JSRInlinerAdapter.visitEnd(JSRInlinerAdapter.java:159)
	at org.objectweb.asm.ClassReader.readMethod(ClassReader.java:1516)
	at org.objectweb.asm.ClassReader.accept(ClassReader.java:745)
	at org.objectweb.asm.ClassReader.accept(ClassReader.java:425)
	at org.apache.aries.spifly.dynamic.ClientWeavingHook.weave(ClientWeavingHook.java:60)
	at org.eclipse.osgi.internal.weaving.WovenClassImpl.call(WovenClassImpl.java:194)
	at org.eclipse.osgi.internal.weaving.WovenClassImpl.call(WovenClassImpl.java:1)
	at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.notifyHookPrivileged(ServiceRegistry.java:1442)
	at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.notifyHooksPrivileged(ServiceRegistry.java:1415)
	at org.eclipse.osgi.internal.weaving.WovenClassImpl.callHooks(WovenClassImpl.java:269)
	at org.eclipse.osgi.internal.weaving.WeavingHookConfigurator.processClass(WeavingHookConfigurator.java:85)
	... 51 more

[chrisrueger]

@tjwatson I have taken your comments and extended the docs a little bit #1172

[chrisrueger]

Just when I was on this I remembered #853 which I think would be very cool to have on day 😄

[laeubi]

Its on my Agenda and I actually have implemented such support recently in Tycho just in a litte different context:

• https://github.com/eclipse-tycho/tycho/blob/main/tycho-test-plugin/src/main/java/org/eclipse/tycho/testing/plugin/SPIBundleClassLoader.java