This exception happens when server is starting.

WARNING: Failed to load hudson.model.queue.Messages for public static void hudson.model.queue.QueueSorter.installDefaultQueueSorter()
java.lang.ClassNotFoundException: hudson.model.queue.Messages
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1387)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1233)
at hudson.init.InitializerFinder.getDisplayNameOf(InitializerFinder.java:84)
at hudson.init.InitializerFinder$TaskImpl.getDisplayName(InitializerFinder.java:160)
at hudson.model.Hudson$4.onTaskStarted(Hudson.java:684)
at org.jvnet.hudson.reactor.ReactorListener$Aggregator.onTaskStarted(ReactorListener.java:66)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:185)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:94)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
Feb 3, 2010 11:46:45 AM hudson.init.InitializerFinder getDisplayNameOf
WARNING: Failed to load hudson.model.queue.Messages for public static void hudson.model.queue.QueueSorter.installDefaultQueueSorter()
java.lang.ClassNotFoundException: hudson.model.queue.Messages
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1387)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1233)
at hudson.init.InitializerFinder.getDisplayNameOf(InitializerFinder.java:84)
at hudson.init.InitializerFinder$TaskImpl.getDisplayName(InitializerFinder.java:160)
at hudson.model.Hudson$3.runTask(Hudson.java:640)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:187)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:94)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
Feb 3, 2010 11:46:49 AM hudson.init.InitializerFinder getDisplayNameOf
WARNING: Failed to load hudson.model.queue.Messages for public static void hudson.model.queue.QueueSorter.installDefaultQueueSorter()
java.lang.ClassNotFoundException: hudson.model.queue.Messages
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1387)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1233)
at hudson.init.InitializerFinder.getDisplayNameOf(InitializerFinder.java:84)
at hudson.init.InitializerFinder$TaskImpl.getDisplayName(InitializerFinder.java:160)
at hudson.model.Hudson$4.onTaskCompleted(Hudson.java:688)
at org.jvnet.hudson.reactor.ReactorListener$Aggregator.onTaskCompleted(ReactorListener.java:71)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:188)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:94)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)