Can you please help understand below error in SonarQube v5.0.
ERROR localhost-startStop-1 web[o.a.c.c.C.[.[.[/]] Exception sending context initialized event to listener instance of class org.sonar.server.platform.PlatformServletContextListener java.lang.IllegalStateException: Could not execute normalization for stack
at org.sonar.server.search.IndexQueue.processActionsIntoQueries(IndexQueue.java:142) ~[sonar-server-5.0.jar:na]
at org.sonar.server.search.IndexQueue.enqueue(IndexQueue.java:78) ~[sonar-server-5.0.jar:na]
at org.sonar.core.persistence.DbSession.commit(DbSession.java:62) ~[sonar-core-5.0.jar:na]
at org.sonar.server.db.BaseDao.synchronizeAfter(BaseDao.java:361) ~[sonar-server-5.0.jar:na]
at org.sonar.server.db.BaseDao.synchronizeAfter(BaseDao.java:347) ~[sonar-server-5.0.jar:na]
at org.sonar.server.search.IndexSynchronizer.synchronize(IndexSynchronizer.java:79) ~[sonar-server-5.0.jar:na]
at org.sonar.server.search.IndexSynchronizer.execute(IndexSynchronizer.java:59) ~[sonar-server-5.0.jar:na]
at org.sonar.server.platform.ServerComponents$1.doPrivileged(ServerComponents.java:664) ~[sonar-server-5.0.jar:na]
at org.sonar.server.user.DoPrivileged.execute(DoPrivileged.java:43) ~[sonar-server-5.0.jar:na]
at org.sonar.server.platform.ServerComponents.executeStartupTasks(ServerComponents.java:661) ~[sonar-server-5.0.jar:na]
at org.sonar.server.platform.Platform.executeStartupTasks(Platform.java:126) ~[sonar-server-5.0.jar:na]
at org.sonar.server.platform.Platform.startLevel34Containers(Platform.java:122) ~[sonar-server-5.0.jar:na]
at org.sonar.server.platform.Platform.doStart(Platform.java:81) ~[sonar-server-5.0.jar:na]
at org.sonar.server.platform.PlatformServletContextListener.contextInitialized(PlatformServletContextListener.java:44) ~[sonar-server-5.0.jar:na]
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4973) [tomcat-embed-core-7.0.54.jar:7.0.54]
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5467) [tomcat-embed-core-7.0.54.jar:7.0.54]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) [tomcat-embed-core-7.0.54.jar:7.0.54]
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559) [tomcat-embed-core-7.0.54.jar:7.0.54]
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549) [tomcat-embed-core-7.0.54.jar:7.0.54]
at java.util.concurrent.FutureTask.run(FutureTask.java:262) [na:1.7.0_241]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1152) [na:1.7.0_241]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:622) [na:1.7.0_241]
at java.lang.Thread.run(Thread.java:748) [na:1.7.0_241]
Caused by: java.util.concurrent.CancellationException: null
at java.util.concurrent.FutureTask.report(FutureTask.java:121) [na:1.7.0_241]
at java.util.concurrent.FutureTask.get(FutureTask.java:188) [na:1.7.0_241]
at org.sonar.server.search.IndexQueue.processActionsIntoQueries(IndexQueue.java:124) ~[so