When restarting an agent after a successful agent upgrade, seeing [IntroscopeAgent.Agent] java.lang.NoSuchMethodError Exception.
APM all releases and IBM JRE
The code is cached, causing the apparent conflict/file corruption.
Clear the share class cache for IBM JVM by restarting the application with the IBM Java option -Xshareclasses:none or -Xshareclasses:reset, added to the JVM startup arguments.
-Xshareclasses:none starts the application without using the cache and shared classes. This can be a useful short-term solution to confirm that it is a cache related problem.
-Xshareclasses:reset starts the application, with shared classes, then clears the cache and rebuilds it. This is the recommended solution to fix a problem with the cache.