Faces config ConfigurationException happens randomly

I get the following error sometime on re-deployment of the application (its not consistent though). Does anyone know why this would happen?

10:08:44,703 INFO  [TomcatDeployment] deploy, ctxPath=/abc
10:08:44,886 INFO  [config] Initializing Mojarra (1.2_12-b01-FCS) for conte
xt '/abc'
10:08:44,987 ERROR [[/abc]] Exception sending context initialized event to
listener instance of class org.jboss.web.jsf.integration.config.JBossJSFCon
figureListener
com.sun.faces.config.ConfigurationException: CONFIGURATION FAILED!
  Source Document: jndi开发者_JAVA技巧:/localhost/abc/WEB-INF/faces-config.xml
  Cause: Unable to find class 'com.sun.facelets.FaceletViewHandler'
        at com.sun.faces.config.ConfigManager.initialize(ConfigManager.java
:213)
        at com.sun.faces.config.ConfigureListener.contextInitialized(Config
ureListener.java:196)
        at org.jboss.web.jsf.integration.config.JBossJSFConfigureListener.c
ontextInitialized(JBossJSFConfigureListener.java:60)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardC
ontext.java:3910)
        at org.apache.catalina.core.StandardContext.start(StandardContext.j
ava:4393)
        at org.jboss.web.tomcat.service.deployers.TomcatDeployment.performD
eployInternal(TomcatDeployment.java:310)
        at org.jboss.web.tomcat.service.deployers.TomcatDeployment.performD
eploy(TomcatDeployment.java:142)
        at org.jboss.web.deployers.AbstractWarDeployment.start(AbstractWarD
eployment.java:461)
        at org.jboss.web.deployers.WebModule.startModule(WebModule.java:118
)
        at org.jboss.web.deployers.WebModule.start(WebModule.java:97)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessor
Impl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethod
AccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDis
patcher.java:157)
        at org.jboss.mx.server.Invocation.dispatch(Invocation.java:96)
        at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
        at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInv
oker.java:264)
        at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:
668)
        at org.jboss.system.microcontainer.ServiceProxy.invoke(ServiceProxy
.java:206)
        at $Proxy38.start(Unknown Source)
        at org.jboss.system.microcontainer.StartStopLifecycleAction.install
Action(StartStopLifecycleAction.java:42)
        at org.jboss.system.microcontainer.StartStopLifecycleAction.install
Action(StartStopLifecycleAction.java:37)
        at org.jboss.dependency.plugins.action.SimpleControllerContextActio
n.simpleInstallAction(SimpleControllerContextAction.java:62)
        at org.jboss.dependency.plugins.action.AccessControllerContextActio
n.install(AccessControllerContextAction.java:71)
        at org.jboss.dependency.plugins.AbstractControllerContextActions.in
stall(AbstractControllerContextActions.java:51)
        at org.jboss.dependency.plugins.AbstractControllerContext.install(A
bstractControllerContext.java:348)
        at org.jboss.system.microcontainer.ServiceControllerContext.install
(ServiceControllerContext.java:286)
        at org.jboss.dependency.plugins.AbstractController.install(Abstract
Controller.java:1631)
        at org.jboss.dependency.plugins.AbstractController.incrementState(A
bstractController.java:934)
        at org.jboss.dependency.plugins.AbstractController.resolveContexts(
AbstractController.java:1082)
        at org.jboss.dependency.plugins.AbstractController.resolveContexts(
AbstractController.java:984)
        at org.jboss.dependency.plugins.AbstractController.change(AbstractC
ontroller.java:822)
        at org.jboss.dependency.plugins.AbstractController.change(AbstractC
ontroller.java:553)
        at org.jboss.system.ServiceController.doChange(ServiceController.ja
va:688)
        at org.jboss.system.ServiceController.start(ServiceController.java:
460)
        at org.jboss.system.deployers.ServiceDeployer.start(ServiceDeployer
.java:163)
        at org.jboss.system.deployers.ServiceDeployer.deploy(ServiceDeploye
r.java:99)
        at org.jboss.system.deployers.ServiceDeployer.deploy(ServiceDeploye
r.java:46)
        at org.jboss.deployers.spi.deployer.helpers.AbstractSimpleRealDeplo
yer.internalDeploy(AbstractSimpleRealDeployer.java:62)
        at org.jboss.deployers.spi.deployer.helpers.AbstractRealDeployer.de
ploy(AbstractRealDeployer.java:50)
        at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(Dep
loyerWrapper.java:171)
        at org.jboss.deployers.plugins.deployers.DeployersImpl.doDeploy(Dep
loyersImpl.java:1439)
        at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallPar
entFirst(DeployersImpl.java:1157)
        at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallPar
entFirst(DeployersImpl.java:1178)
        at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallPar
entFirst(DeployersImpl.java:1210)
        at org.jboss.deployers.plugins.deployers.DeployersImpl.install(Depl
oyersImpl.java:1098)
        at org.jboss.dependency.plugins.AbstractControllerContext.install(A
bstractControllerContext.java:348)
        at org.jboss.dependency.plugins.AbstractController.install(Abstract
Controller.java:1631)
        at org.jboss.dependency.plugins.AbstractController.incrementState(A
bstractController.java:934)
        at org.jboss.dependency.plugins.AbstractController.resolveContexts(
AbstractController.java:1082)
        at org.jboss.dependency.plugins.AbstractController.resolveContexts(
AbstractController.java:984)
        at org.jboss.dependency.plugins.AbstractController.change(AbstractC
ontroller.java:822)
        at org.jboss.dependency.plugins.AbstractController.change(AbstractC
ontroller.java:553)
        at org.jboss.deployers.plugins.deployers.DeployersImpl.process(Depl
oyersImpl.java:781)
        at org.jboss.deployers.plugins.main.MainDeployerImpl.process(MainDe
ployerImpl.java:702)
        at org.jboss.system.server.profileservice.repository.MainDeployerAd
apter.process(MainDeployerAdapter.java:117)
        at org.jboss.system.server.profileservice.hotdeploy.HDScanner.scan(
HDScanner.java:362)
        at org.jboss.system.server.profileservice.hotdeploy.HDScanner.run(H
DScanner.java:255)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.ja
va:441)
        at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask
.java:317)
        at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150)

        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFuture
Task.access$101(ScheduledThreadPoolExecutor.java:98)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFuture
Task.runPeriodic(ScheduledThreadPoolExecutor.java:181)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFuture
Task.run(ScheduledThreadPoolExecutor.java:205)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoo
lExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExe
cutor.java:908)
        at java.lang.Thread.run(Thread.java:619)

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This means your jsf-facelets-1.1.x.jar is missing from WEB-INF/lib