JAVA Agent - Websphere not starting up with agent installed

Elasticsearch version: 7.3.1

APM Server version: 7.3.1

APM Agent language and version: JAVA agent 1.9.0

Websphere Application Server version: 8.5.5.0, Single cell-node-server configuration.

Description of the problem: Websphere fails to startup with startServer.cmd script when Java agent is installed.

We are attempting to monitor performance of a java application deployed in this appserver using the APM java agent.
Following this guide, we added the following generic arguments to the appserver:

-javaagent:D:/WAS/lib/elastic-apm-agent-1.9.0.jar
-Delastic.apm.service_name=my-apm-service
-Delastic.apm.application_packages=com.my.app.package
-Delastic.apm.server_urls=http://localhost:8200

However, when attempting to start up the local server using the startup script it fails and generates the following errors in the logs:

Failed to load transport channel: com.ibm.wsspi.channel.framework.exception.InvalidChannelFactoryException: com.ibm.ws.webcontainer.channel.WCChannelFactory cannot be loaded 
	at com.ibm.ws.channel.framework.impl.WSChannelFrameworkImpl.addChannelFromFactory(WSChannelFrameworkImpl.java:567)
	at com.ibm.ws.channel.framework.impl.WSChannelFrameworkImpl.addChannel(WSChannelFrameworkImpl.java:420)
	at com.ibm.ws.runtime.component.ChannelFrameworkServiceImpl.addChannel(ChannelFrameworkServiceImpl.java:821)
	at com.ibm.ws.runtime.component.ChannelFrameworkServiceImpl.initialize(ChannelFrameworkServiceImpl.java:369)
	at com.ibm.ws.runtime.component.ContainerHelper.initWsComponent(ContainerHelper.java:1192)
	at com.ibm.ws.runtime.component.ContainerHelper.initializeComponent(ContainerHelper.java:1099)
	at com.ibm.ws.runtime.component.ContainerHelper.initializeComponents(ContainerHelper.java:901)
	at com.ibm.ws.runtime.component.ContainerImpl.initializeComponents(ContainerImpl.java:776)
	at com.ibm.ws.runtime.component.ContainerImpl.initializeComponents(ContainerImpl.java:750)
	at com.ibm.ws.runtime.component.ServerImpl.initialize(ServerImpl.java:353)
	at com.ibm.ws.runtime.WsServerImpl.bootServerContainer(WsServerImpl.java:292)
	at com.ibm.ws.runtime.WsServerImpl.start(WsServerImpl.java:223)
	at com.ibm.ws.runtime.WsServerImpl.main(WsServerImpl.java:686)
	at com.ibm.ws.runtime.WsServer.main(WsServer.java:59)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:95)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:56)
	at java.lang.reflect.Method.invoke(Method.java:620)
	at com.ibm.wsspi.bootstrap.WSLauncher.launchMain(WSLauncher.java:234)
	at com.ibm.wsspi.bootstrap.WSLauncher.main(WSLauncher.java:96)
	at com.ibm.wsspi.bootstrap.WSLauncher.run(WSLauncher.java:77)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:95)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:56)
	at java.lang.reflect.Method.invoke(Method.java:620)
	at org.eclipse.equinox.internal.app.EclipseAppContainer.callMethodWithException(EclipseAppContainer.java:587)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:198)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:369)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:95)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:56)
	at java.lang.reflect.Method.invoke(Method.java:620)
	at org.eclipse.core.launcher.Main.invokeFramework(Main.java:340)
	at org.eclipse.core.launcher.Main.basicRun(Main.java:282)
	at org.eclipse.core.launcher.Main.run(Main.java:981)
	at com.ibm.wsspi.bootstrap.WSPreLauncher.launchEclipse(WSPreLauncher.java:379)
	at com.ibm.wsspi.bootstrap.WSPreLauncher.main(WSPreLauncher.java:150)
Caused by: java.lang.NoClassDefFoundError: com.ibm.wsspi.channel.base.ApplicationChannelFactory
	at java.lang.ClassLoader.defineClassImpl(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:324)
	at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.defineClass(DefaultClassLoader.java:188)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.defineClass(ClasspathManager.java:580)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findClassImpl(ClasspathManager.java:550)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClassImpl(ClasspathManager.java:481)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass_LockClassName(ClasspathManager.java:460)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass(ClasspathManager.java:447)
	at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.findLocalClass(DefaultClassLoader.java:216)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:393)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:469)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:422)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:410)
	at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:731)
	at org.eclipse.osgi.internal.loader.BundleLoader.loadClass(BundleLoader.java:338)
	at org.eclipse.osgi.framework.internal.core.BundleHost.loadClass(BundleHost.java:232)
	at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadClass(AbstractBundle.java:1197)
	at com.ibm.ws.channel.framework.ctm.BaseChannelTypeManager$OSGiChannelMetaDataImpl$1.run(BaseChannelTypeManager.java:392)
	at com.ibm.ws.channel.framework.ctm.BaseChannelTypeManager$OSGiChannelMetaDataImpl$1.run(BaseChannelTypeManager.java:390)
	at java.security.AccessController.doPrivileged(AccessController.java:456)
	at com.ibm.ws.security.util.AccessController.doPrivileged(AccessController.java:125)
	at com.ibm.ws.channel.framework.ctm.BaseChannelTypeManager$OSGiChannelMetaDataImpl.getClass(BaseChannelTypeManager.java:390)
	at com.ibm.ws.channel.framework.impl.WSChannelFrameworkImpl.addChannelFromFactory(WSChannelFrameworkImpl.java:557)
	... 39 more

Hi and welcome to the forum!
WebSphere Application Server is not supported yet, only WebSphere Liberty.
We do intend to support it, but there is no concrete schedule for that yet.