When enabling APM Java Agent within JVM arguments for an Application Server this error is being logged:
Error opening zip file or JAR manifest missing : /opt/tools/introscope/R101015/wily/Agent.jar
Error occurred during initialization of VM agent library failed to init: instrument
In addition no Agent logs are being created.
There are multiple reasons that could cause this issue/error to show up during initialization of JVM such as:
Unix user id that was running the application server didn't have read permissions to the top level Agent installation directory, as a result of which it was failing to load the Agent.jar. Providing required read/write/execute permissions on the Agent install folder should address the issue.