Hi,
I don’t know if it was you but this was also raised in jira at
https://jira.xwiki.org/browse/XE-1610
I don’t know the answer as this stage but it looks very weird. I’m sure someone will
provide a solution by tomorrow EOD.
Thanks
-Vincent
  On 8 Feb 2017, at 18:42, Ligth
<ya.est.svet(a)yandex.ru> wrote:
 Hi.
 We  have upgraded  xwiki  enterprise   from  8  to  9.0 versionb  on  debian:
 apt-get  update &&  apt-get  upgrade
 # dpkg -l | grep xwiki
 ii  xwiki-enterprise-common         9.0+3
 ii  xwiki-enterprise-pgsql-common   9.0+3
 ii  xwiki-enterprise-tomcat8-common 9.0+3
 ii  xwiki-enterprise-tomcat8-pgsql  9.0+3
 And  now  we  can't  get  started  xwiki.  The  following  error is  received:
 SEVERE: Exception sending context initialized event to listener instance of class
org.xwiki.container.servlet.XWikiServletContextListener
 java.lang.NoClassDefFoundError: Failed to get fields for class
[org.xwiki.activeinstalls.internal.client.DefaultPingSender] because the class
[io/searchbox/Action] couldn't be found in the ClassLoader.
        at org.xwiki.component.util.ReflectionUtils.getAllFields(ReflectionUtils.java:72)
        at
org.xwiki.component.annotation.ComponentDescriptorFactory.createComponentDescriptor(ComponentDescriptorFactory.java:132)
        at
org.xwiki.component.annotation.ComponentDescriptorFactory.createComponentDescriptors(ComponentDescriptorFactory.java:105)
        at
org.xwiki.component.annotation.ComponentAnnotationLoader.register(ComponentAnnotationLoader.java:168)
        at
org.xwiki.component.annotation.ComponentAnnotationLoader.initialize(ComponentAnnotationLoader.java:136)
        at
org.xwiki.component.annotation.ComponentAnnotationLoader.initialize(ComponentAnnotationLoader.java:118)
        at
org.xwiki.component.embed.EmbeddableComponentManager.initialize(EmbeddableComponentManager.java:151)
        at
org.xwiki.container.servlet.XWikiServletContextListener.contextInitialized(XWikiServletContextListener.java:61)
        at
org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4832)
        at
org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5256)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:724)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:700)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:714)
        at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:581)
        at
org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1685)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
 фев 08, 2017 6:03:35 PM org.apache.catalina.core.StandardContext startInternal
 SEVERE: Error listenerStart
 Can  someone   help ?