WSO2 Carbon Sever Startup Exception - Failed to activate Carbon Application Deployer

You might get the following exception while starting any WSO2 Carbon Server.

TID: [0] [IS] [2015-06-17 16:33:07,706] ERROR
{org.wso2.carbon.application.deployer.internal.AppDeployerServiceComponent} - Failed to activate Carbon Application Deployer {org.wso2.carbon.application.deployer.internal.AppDeployerServiceComponent} java.lang.ExceptionInInitializerError
at org.wso2.carbon.application.deployer.internal.ApplicationManager.findInitialHandlerCount(ApplicationManager.java:765)
at org.wso2.carbon.application.deployer.internal.ApplicationManager.init(ApplicationManager.java:107)
at org.wso2.carbon.application.deployer.internal.AppDeployerServiceComponent.activate(AppDeployerServiceComponent.java:77)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.internal.ds.model.ServiceComponent.activate(ServiceComponent.java:260)
at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.activate(ServiceComponentProp.java:146)
at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.build(ServiceComponentProp.java:347)
at org.eclipse.equinox.internal.ds.InstanceProcess.buildComponent(InstanceProcess.java:620)
at org.eclipse.equinox.internal.ds.InstanceProcess.buildComponents(InstanceProcess.java:197)
at org.eclipse.equinox.internal.ds.Resolver.getEligible(Resolver.java:343)
at org.eclipse.equinox.internal.ds.SCRManager.serviceChanged(SCRManager.java:222)
at org.eclipse.osgi.internal.serviceregistry.FilteredServiceListener.serviceChanged(FilteredServiceListener.java:107)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.dispatchEvent(BundleContextImpl.java:861)
at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:148)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.publishServiceEventPrivileged(ServiceRegistry.java:819)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.publishServiceEvent(ServiceRegistry.java:771)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistrationImpl.register(ServiceRegistrationImpl.java:130)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.registerService(ServiceRegistry.java:214)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.registerService(BundleContextImpl.java:433)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.registerService(BundleContextImpl.java:451)
at org.wso2.carbon.core.init.CarbonServerManager.initializeCarbon(CarbonServerManager.java:517)
at org.wso2.carbon.core.init.CarbonServerManager.start(CarbonServerManager.java:219)
at org.wso2.carbon.core.internal.CarbonCoreServiceComponent.activate(CarbonCoreServiceComponent.java:77)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.internal.ds.model.ServiceComponent.activate(ServiceComponent.java:260)
at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.activate(ServiceComponentProp.java:146)
at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.build(ServiceComponentProp.java:347)
at org.eclipse.equinox.internal.ds.InstanceProcess.buildComponent(InstanceProcess.java:620)
at org.eclipse.equinox.internal.ds.InstanceProcess.buildComponents(InstanceProcess.java:197)
at org.eclipse.equinox.internal.ds.Resolver.getEligible(Resolver.java:343)
at org.eclipse.equinox.internal.ds.SCRManager.serviceChanged(SCRManager.java:222)
at org.eclipse.osgi.internal.serviceregistry.FilteredServiceListener.serviceChanged(FilteredServiceListener.java:107)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.dispatchEvent(BundleContextImpl.java:861)
at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:148)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.publishServiceEventPrivileged(ServiceRegistry.java:819)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.publishServiceEvent(ServiceRegistry.java:771)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistrationImpl.register(ServiceRegistrationImpl.java:130)
at org.eclipse.osgi.internal.serviceregistry.ServiceRegistry.registerService(ServiceRegistry.java:214)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.registerService(BundleContextImpl.java:433)
at org.eclipse.equinox.http.servlet.internal.Activator.registerHttpService(Activator.java:81)
at org.eclipse.equinox.http.servlet.internal.Activator.addProxyServlet(Activator.java:60)
at org.eclipse.equinox.http.servlet.internal.ProxyServlet.init(ProxyServlet.java:40)
at org.wso2.carbon.tomcat.ext.servlet.DelegationServlet.init(DelegationServlet.java:38)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1267)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1186)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1081)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5027)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5314)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
at org.wso2.carbon.application.deployer.AppDeployerUtils.createDir(AppDeployerUtils.java:713)
at org.wso2.carbon.application.deployer.AppDeployerUtils.(AppDeployerUtils.java:77)
... 63 more

Here is the reason why this exception can be thrown and how to solve it.

At the startup of a Carbon Server (ESB, IS, APIM, etc), it creates a directory named "work" under the location "$CARBON_HOME/repository/carbonapps/". We will see the above exception, if it fails to create this particular directory at the startup. There can be several reason for this. Some of them are,

• It could be a permission issue in the file system. To solve it, change the permission.
• It could be because the "$CARBON_HOME/repository/carbonapps/" directory does not exist. It can happen with some unzipping tools as they don't extract recursive empty folders. The carbonapps folder is an empty folder which is included in any Carbon Server pack by default. You can either create this directory manually or use a correct unzipping tools to solve this issue.

 Double checking above two things will probably solve this issue.