After setting up the APM Java Agent with Websphere Liberty at the common configuration level (<Liberty_Home>/etc/jvm.options), the agent fails to load with errors such as:
Error opening zip file or JAR manifest missing : "/Agent/wily/Agent.jar"
JVMJ9TI064E Agent initialization function Agent_OnLoad failed for library instrument, return code -1
JVMJ9VM015W Initialization error for library j9jvmti28(-3): JVMJ9VM009E J9VMDllMain failed
Rather than configuring Liberty to use the agent at the common configuration level, this should be done at the server level (<Liberty_Home>/usr/servers/<Liberty_Server_Name>/jvm.options).
If after trying this option the agent still fails to load, please open a Support issue and reference this KB.