Error attaching this container for rendering: [Item [Component id = 2]]

Hi, guys. Have an error after clearing redundant config files. How can I find this component:

Error attaching this container for rendering: [Item [Component id = 2]]

But I think that problem is not in my clearing. Also I added a lot of new components. How can I resolve this problem? Thanks a lot.

09.07.2019 14:37:25 [http-nio-8080-exec-4] ERROR [org.apache.wicket.DefaultExceptionMapper.mapUnexpectedExceptions():170] Unexpected error occurred                                                                                                                               
    org.apache.wicket.WicketRuntimeException: Error attaching this container for rendering: [Item [Component id = 2]]                                                                                                                                                                 
            at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1699) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                   
            at org.apache.wicket.Component.onBeforeRender(Component.java:3834) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                                       
            at org.apache.wicket.Component.internalBeforeRender(Component.java:949) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                                  
            at org.apache.wicket.Component.beforeRender(Component.java:1017) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                                         
            at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1687) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                   
            at org.apache.wicket.Component.onBeforeRender(Component.java:3834) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                                       
            at org.apache.wicket.markup.repeater.AbstractRepeater.onBeforeRender(AbstractRepeater.java:143) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                          
            at org.apache.wicket.markup.repeater.AbstractPageableView.onBeforeRender(AbstractPageableView.java:115) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                  
            at org.apache.wicket.Component.internalBeforeRender(Component.java:949) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                                  
            at org.apache.wicket.Component.beforeRender(Component.java:1017) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                                         
            at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1687) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                   
            at org.apache.wicket.Component.onBeforeRender(Component.java:3834) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                                       
            at org.hippoecm.frontend.service.render.AbstractRenderService.onBeforeRender(AbstractRenderService.java:522) ~[hippo-cms-api-5.1.1.jar:5.1.1]                                                                                                                             
            at org.apache.wicket.Component.internalBeforeRender(Component.java:949) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                                  
            at org.apache.wicket.Component.beforeRender(Component.java:1017) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                                         
            at org.apache.wicket.Component.internalPrepareForRender(Component.java:2202) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                             
            at org.apache.wicket.Component.prepareForRender(Component.java:2241) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                                     
            at org.apache.wicket.ajax.XmlAjaxResponse.writeComponent(XmlAjaxResponse.java:107) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                       
            at org.apache.wicket.ajax.AbstractAjaxResponse.writeComponents(AbstractAjaxResponse.java:229) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                            
            at org.apache.wicket.ajax.AbstractAjaxResponse.writeTo(AbstractAjaxResponse.java:154) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                    
            at org.apache.wicket.ajax.AjaxRequestHandler.respond(AjaxRequestHandler.java:359) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                        
            at org.hippoecm.frontend.PluginRequestTarget.respond(PluginRequestTarget.java:150) ~[hippo-cms-api-5.1.1.jar:5.1.1]                                                                                                                                                       
            at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:890) ~[wicket-core-6.29.0.jar:6.29.0]                                                                                                                                           
            at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64) ~[wicket-request-6.29.0.jar:6.29.0]                                                                                                                                                 
            at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:97) ~[wicket-request-6.29.0.jar:6.29.0]                                                                                                                                                 
            at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:261) [wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                            
            at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:218) [wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                     
            at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:289) [wicket-core-6.29.0.jar:6.29.0]                                                                                                                                            
            at org.apache.wicket.protocol.http.WicketFilter.processRequestCycle(WicketFilter.java:259) [wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                
            at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:201) [wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                     
            at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:282) [wicket-core-6.29.0.jar:6.29.0]                                                                                                                                                           
            at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.28]                                                                                                                                                
            at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.28]                                                                                                                                                        
            at org.hippoecm.frontend.plugins.login.ConcurrentLoginFilter.doFilter(ConcurrentLoginFilter.java:54) [hippo-cms-engine-5.1.1.jar:5.1.1]                                                                                                                                   
            at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.28]                                                                                                                                                
            at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.28]                                                                                                                                                        
            at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) [catalina.jar:8.5.28]                                                                                                                                                              
            at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [catalina.jar:8.5.28]                                                                                                                                                               
            at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [catalina.jar:8.5.28]                                                                                                                                                                    
            at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [catalina.jar:8.5.28]                                                                                                                                                                     
            at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650) [catalina.jar:8.5.28]                                                                                                                                                        
            at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [catalina.jar:8.5.28]                                                                                                                                                                 
            at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [catalina.jar:8.5.28]                                                                                                                                                                      
            at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-coyote.jar:8.5.28]                                                                                                                                                                  
            at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-coyote.jar:8.5.28]                                                                                                                                                            
            at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790) [tomcat-coyote.jar:8.5.28]                                                                                                                                                     
            at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459) [tomcat-coyote.jar:8.5.28]                                                                                                                                                         
            at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-coyote.jar:8.5.28]                                                                                                                                                             
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_151]                                                                                                                                                                          
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_151]                                                                                                                                                                          
            at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.5.28]                                                                                                                                                            
            at java.lang.Thread.run(Thread.java:748) [?:1.8.0_151]                                                                                                                                                                                                                    
    Caused by: java.lang.NullPointerException                                                                                                                                                                                                                                         
            at org.hippoecm.frontend.editor.plugins.field.ComparingController.start(ComparingController.java:270) ~[hippo-cms-editor-frontend-5.1.1.jar:5.1.1]                                                                                                                        
            at org.hippoecm.frontend.editor.plugins.field.AbstractFieldPlugin.onBeforeRender(AbstractFieldPlugin.java:330) ~[hippo-cms-editor-frontend-5.1.1.jar:5.1.1]                                                                                                               
            at org.hippoecm.frontend.editor.plugins.field.NodeFieldPlugin.onBeforeRender(NodeFieldPlugin.java:131) ~[hippo-cms-editor-frontend-5.1.1.jar:5.1.1]                                                                                                                       
            at org.apache.wicket.Component.internalBeforeRender(Component.java:949) ~[wicket-core-6.29.0.jar:6.29.0]