Why does the Analytic Agent fail to start?

[#1]

Analytics Agent refuses to start and the Machine Agent or Analytics Agent logs contain an exception

Problem

You may come across an issue where the Analytics Agent refuses to start up due to the java.lang.NoSuchMethodError: io.dropwizard.logging.LoggingFactory.bootstrap and the Machine Agent or Analytics Agent logs contain an exception, as shown below.

[system-thread-0] 13 Dec 2017 11:29:58,129 FATAL InProcessLauncherTask - Error occurred while attempting to load the task [{csvMethodArgs=/app/perf/appdynamics/ma/monitors/analytics-agent/conf/analytics-agent.properties, methodName=main, className=com.appdynamics.analytics.agent.AnalyticsAgent}]
java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at com.singularity.ee.agent.systemagent.task.util.InProcessLauncherTask.launch(InProcessLauncherTask.java:185)
        at com.singularity.ee.agent.systemagent.task.util.InProcessLauncherTask.execute(InProcessLauncherTask.java:149)
        at com.singularity.ee.agent.systemagent.task.analytics.AnalyticsAgentLauncher.execute(AnalyticsAgentLauncher.java:63)
        at com.singularity.ee.agent.systemagent.components.monitormanager.managed.MonitorTaskRunner.runTask(MonitorTaskRunner.java:148)
        at com.singularity.ee.agent.systemagent.components.monitormanager.managed.ScheduledTaskRunner.run(ScheduledTaskRunner.java:41)
        at com.singularity.ee.agent.systemagent.components.monitormanager.managed.ManagedMonitorDelegate.setupEnvTask(ManagedMonitorDelegate.java:272)
        at com.singularity.ee.agent.systemagent.components.monitormanager.managed.ManagedMonitorDelegate.initializeMonitor(ManagedMonitorDelegate.java:211)
        at com.singularity.ee.agent.systemagent.components.monitormanager.NodeMonitorManager.readConfig(NodeMonitorManager.java:179)
        at com.singularity.ee.agent.systemagent.components.monitormanager.NodeMonitorManager.startAllMonitors(NodeMonitorManager.java:261)
        at com.singularity.ee.agent.systemagent.components.monitormanager.NodeMonitorManager.<init>(NodeMonitorManager.java:78)
        at com.singularity.ee.agent.systemagent.components.monitormanager.AgentMonitorManager.<init>(AgentMonitorManager.java:61)
        at com.singularity.ee.agent.systemagent.Agent.setupMonitorManager(Agent.java:446)
        at com.singularity.ee.agent.systemagent.Agent.startServices(Agent.java:358)
        at com.singularity.ee.agent.systemagent.SystemAgent.startServices(SystemAgent.java:68)
        at com.singularity.ee.agent.systemagent.Agent.start(Agent.java:343)
        at com.appdynamics.agent.sim.legacy.DefaultLegacyAgentRegistrationStateManager$1.run(DefaultLegacyAgentRegistrationStateManager.java:80)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NoSuchMethodError: io.dropwizard.logging.LoggingFactory.bootstrap()V
        at io.dropwizard.Application.<clinit>(Application.java:20)
        at com.appdynamics.analytics.agent.AnalyticsAgent.validateAndMakeArgs(AnalyticsAgent.java:66)
        at com.appdynamics.analytics.agent.AnalyticsAgent.main(AnalyticsAgent.java:89)
        ... 27 more

This is normally caused due to the presence of duplicate jar file from a different version of the Analytics Agent.

Solution

This normally occurs when one unzips new version of their machine-agent.zip into the same directory where the older machine-agent resides. The duplicate presence of the same jar files from both versions prevents the server from starting up.

To resolve the issue:

1. Take a backup of the old Machine Agent
2. Delete or rename the Machine Agent
3. Unzip the new machine-agent.zip

On completing these steps, the Analytics Agent will start up as expected.