java.lang.VerifyError: Cannot inherit from final class

Problem: "java.lang.VerifyError: Cannot inherit from final class" Error seen in JBOSS Server.log file.

2012-10-09 12:47:47,886 WARN  [org.jboss.detailed.classloader.ClassLoaderManager] (MT-AIR_XMLRPC_02) Unexpected error during load of:org.apache.http.params.SyncBasicHttpParams
java.lang.VerifyError: Cannot inherit from final class
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
    at org.jboss.classloader.spi.base.BaseClassLoader.access$200(BaseClassLoader.java:63)
    at org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:572)
    at org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:532)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:530)
    at org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:507)
    at org.jboss.classloader.spi.base.BaseDelegateLoader.loadClass(BaseDelegateLoader.java:134)
    at org.jboss.classloader.spi.filter.FilteredDelegateLoader.loadClass(FilteredDelegateLoader.java:131)
    at org.jboss.classloader.spi.base.ClassLoadingTask$ThreadTask.run(ClassLoadingTask.java:452)
    at org.jboss.classloader.spi.base.ClassLoaderManager.nextTask(ClassLoaderManager.java:251)
    at org.jboss.classloader.spi.base.ClassLoaderManager.process(ClassLoaderManager.java:150)
    at org.jboss.classloader.spi.base.BaseClassLoaderDomain.loadClass(BaseClassLoaderDomain.java:265)
    at org.jboss.classloader.spi.base.BaseClassLoaderDomain.loadClass(BaseClassLoaderDomain.java:1119)
    at org.jboss.classloader.spi.base.BaseClassLoader.loadClassFromDomain(BaseClassLoader.java:798)
    at org.jboss.classloader.spi.base.BaseClassLoader.loadClass(BaseClassLoader.java:441)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
    at org.apache.http.impl.client.DefaultHttpClient.createHttpParams(DefaultHttpClient.java:161)
    at org.apache.http.impl.client.AbstractHttpClient.getParams(AbstractHttpClient.java:426)
    at org.apache.xmlrpc.XmlRpcHttpClient.setConnectTimeout(XmlRpcHttpClient.java:306)


Solution: java.lang.VerifyError comes when a component is not able to identify the jar file at the run time. Check on your server, if you have two different jars of different versions for the same component.

(HDScanner) Scan failed problem in JBOSS Application Server

Problem: When does the problem of (HDScanner) Scan failed comes with below kind of JBOSS Server.log

2012-10-15 06:51:59,343 WARN  [org.jboss.system.server.profileservice.hotdeploy.HDScanner] (HDScanner) Scan failed
java.io.IOException: Error listing files: /opt/jboss-5.1.0.GA/server/prod-deploy/tmp/3j001-okh8ua-h8b3sdna-1-h8b3srrc-t/admin-console.war
        at org.jboss.virtual.plugins.context.file.FileHandler.getChildren(FileHandler.java:225)
        at org.jboss.virtual.plugins.context.AbstractVFSContext.getChildren(AbstractVFSContext.java:219)
        at org.jboss.virtual.plugins.context.AbstractVFSContext.visit(AbstractVFSContext.java:336)
        at org.jboss.virtual.plugins.context.AbstractVFSContext.visit(AbstractVFSContext.java:306)
        at org.jboss.virtual.VFS.visit(VFS.java:421)
        at org.jboss.virtual.VirtualFile.visit(VirtualFile.java:437)
        at org.jboss.deployers.vfs.spi.structure.modified.SynchWrapperModificationChecker.hasStructureBeenModifed(SynchWrapperModificationChecker.java:90)
        at org.jboss.deployers.vfs.spi.structure.modified.AbstractStructureModificationChecker.hasStructureBeenModified(AbstractStructureModificationChecker.java:195)
        at org.jboss.deployers.vfs.spi.structure.modified.AbstractStructureModificationChecker.hasStructureBeenModified(AbstractStructureModificationChecker.java:138)
        at org.jboss.system.server.profileservice.repository.HotDeploymentRepository.getModifiedDeployments(HotDeploymentRepository.java:120)
        at org.jboss.system.server.profile.repository.AbstractProfile.getModifiedDeployments(AbstractProfile.java:128)
        at org.jboss.system.server.profileservice.hotdeploy.HDScanner.scan(HDScanner.java:336)
        at org.jboss.system.server.profileservice.hotdeploy.HDScanner.run(HDScanner.java:255)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
        at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:317)
        at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:98)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:181)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:205)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:619)

Solution: This problem occurs when data from  <JBOSS_DIR>/server/default/tmp  is removed at the run time, means at the time when application is running and data from this directory is removed, then JBOSS Server won't be able to serve any request coming and above error messages will be seen in the JBOSS Server.log file.