Getting the below Log error,

Any suggestions for debugging please.

java.lang.RuntimeException: caught exception while expanding property payload on page
 at com.pega.pegarules.data.internal.clipboard.DirectStreamContainerV7.expandToProperty(DirectStreamContainerV7.java:791)
 at com.pega.pegarules.data.internal.clipboard.DirectStreamContainerV7.expandAllToProperties(DirectStreamContainerV7.java:536)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.expandAll(ClipboardPageImpl.java:1146)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.expandAll(ClipboardPageImpl.java:1140)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.setAsSpecialJavaPage(ClipboardPageImpl.java:4608)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageBase.attachJavaObjectHelper(ClipboardPageBase.java:726)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.attachJavaObjectHelper(ClipboardPageImpl.java:482)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageBase.attachJavaObject(ClipboardPageBase.java:686)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.attachJavaObject(ClipboardPageImpl.java:482)
 at com.pega.pegarules.data.internal.clipboard.DirectStreamContainerV7.addToClipboardObject(DirectStreamContainerV7.java:989)
 at com.pega.pegarules.data.internal.clipboard.DirectStreamContainerV7.applyToPage(DirectStreamContainerV7.java:512)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.adoptStreamForm(ClipboardPageImpl.java:738)
 at com.pega.pegarules.session.internal.mgmt.base.NodeRequestorMgt.readPage(NodeRequestorMgt.java:893)
 at com.pega.pegarules.session.internal.mgmt.base.ThreadPageDir.checkForPassivatedPage(ThreadPageDir.java:634)
 at com.pega.pegarules.session.internal.mgmt.base.ThreadPageDir$PageActivationPassivationListener.onBeforeAccess(ThreadPageDir.java:320)
 at com.pega.pegarules.session.internal.mgmt.base.handler.AbstractPageHandler.onBeforeAccess(AbstractPageHandler.java:106)
 at com.pega.pegarules.session.internal.mgmt.base.handler.UserPageHandler.getPage(UserPageHandler.java:153)
 at com.pega.pegarules.session.internal.mgmt.base.AbstractPageDirectory.getUserPageInCurrentDir(AbstractPageDirectory.java:219)
 at com.pega.pegarules.session.internal.mgmt.base.AbstractPageDirectory.getPage(AbstractPageDirectory.java:1088)
 at com.pega.pegarules.session.internal.mgmt.base.AbstractPageDirectory.getDirectPage(AbstractPageDirectory.java:727)
 at com.pega.pegarules.session.internal.mgmt.base.ThreadPageDir.getDirectPage(ThreadPageDir.java:473)
 at com.pega.pegarules.session.internal.mgmt.base.ThreadPageDir.getPage(ThreadPageDir.java:431)
 at com.pega.pegarules.session.internal.mgmt.PRThreadImpl.getPage(PRThreadImpl.java:539)
 at com.pega.pegarules.session.internal.mgmt.Executable.findPage(Executable.java:2081)
 at com.pega.pegarules.session.internal.mgmt.Executable.findPage(Executable.java:2034)
 at com.pegarules.generated.activity.ra_action_getclaimsbyclaimnumber_0b1bb24d431ce811081588547729c188.perform(ra_action_getclaimsbyclaimnumber_0b1bb24d431ce811081588547729c188.java:141)
 at com.pega.pegarules.session.internal.mgmt.Executable.doActivity(Executable.java:3500)
 at com.pega.pegarules.session.internal.mgmt.Executable.invokeActivity(Executable.java:10521)
 at com.pegarules.generated.activity.ra_action_performsearch_3c317dc8c65f4df53c014d4e49d68f75.step16_circum0(ra_action_performsearch_3c317dc8c65f4df53c014d4e49d68f75.java:1604)
 at com.pegarules.generated.activity.ra_action_performsearch_3c317dc8c65f4df53c014d4e49d68f75.perform(ra_action_performsearch_3c317dc8c65f4df53c014d4e49d68f75.java:337)
 at com.pega.pegarules.session.internal.mgmt.Executable.doActivity(Executable.java:3500)
 at com.pegarules.generated.flow.ra_action_startinquirymainflow_d30b3c75ba99b187506d1c75d5481349.RunTaskActivity(ra_action_startinquirymainflow_d30b3c75ba99b187506d1c75d5481349.java:4340)
 at com.pegarules.generated.flow.ra_action_startinquirymainflow_d30b3c75ba99b187506d1c75d5481349.Task_UTILITY80_circum0(ra_action_startinquirymainflow_d30b3c75ba99b187506d1c75d5481349.java:999)
 at com.pegarules.generated.flow.ra_action_startinquirymainflow_d30b3c75ba99b187506d1c75d5481349.perform(ra_action_startinquirymainflow_d30b3c75ba99b187506d1c75d5481349.java:600)
 at com.pega.pegarules.session.internal.mgmt.Executable.doActivity(Executable.java:3500)
 at com.pegarules.generated.StartFlow_071017_Y4eQmw0Y6OuVgKxzwKWCmA.StartFlow07_10_17(StartFlow_071017_Y4eQmw0Y6OuVgKxzwKWCmA.java:167)
 at com.pegarules.generated.StartFlow_071017_Y4eQmw0Y6OuVgKxzwKWCmA.invoke(StartFlow_071017_Y4eQmw0Y6OuVgKxzwKWCmA.java:76)
 at com.pega.pegarules.generation.internal.library.LibraryRuntime.resolveAndinvokeFunctionViaReflection(LibraryRuntime.java:133)
 at com.pega.pegarules.generation.internal.library.LibraryRuntime.invokeLibraryRuntime(LibraryRuntime.java:110)
 at com.pega.pegarules.session.internal.mgmt.Executable.invokeLibraryRuntime(Executable.java:8954)
 at com.pega.pegarules.priv.generator.LibrarySupport.resolveAndInvokeFunctionViaReflection(LibrarySupport.java:181)
 at com.pegarules.generated.pega_procom_flow.StartFlow(pega_procom_flow.java:702)
 at com.pegarules.generated.activity.ra_action_completeassignment_f7de5d813b994512a60f01863779f693.step24_circum0(ra_action_completeassignment_f7de5d813b994512a60f01863779f693.java:2407)
 at com.pegarules.generated.activity.ra_action_completeassignment_f7de5d813b994512a60f01863779f693.perform(ra_action_completeassignment_f7de5d813b994512a60f01863779f693.java:517)
 at com.pega.pegarules.session.internal.mgmt.Executable.doActivity(Executable.java:3500)
 at com.pegarules.generated.callActivity_071017_xvj4o_pyNDBZ4Gy293rekg.callActivity07_10_17(callActivity_071017_xvj4o_pyNDBZ4Gy293rekg.java:122)
 at com.pegarules.generated.callActivity_071017_xvj4o_pyNDBZ4Gy293rekg.invoke(callActivity_071017_xvj4o_pyNDBZ4Gy293rekg.java:82)
 at com.pega.pegarules.generation.internal.library.LibraryRuntime.resolveAndinvokeFunctionViaReflection(LibraryRuntime.java:133)
 at com.pega.pegarules.generation.internal.library.LibraryRuntime.invokeLibraryRuntime(LibraryRuntime.java:110)
 at com.pega.pegarules.session.internal.mgmt.Executable.invokeLibraryRuntime(Executable.java:8954)
 at com.pega.pegarules.priv.generator.LibrarySupport.resolveAndInvokeFunctionViaReflection(LibrarySupport.java:181)
 at com.pegarules.generated.pega_rules_utilities.callActivity(pega_rules_utilities.java:1743)
 at com.pegarules.generated.activity.ra_action_performflowaction_dcc0518232737c778d7b712de85b2ed5.step18_circum0(ra_action_performflowaction_dcc0518232737c778d7b712de85b2ed5.java:1706)
 at com.pegarules.generated.activity.ra_action_performflowaction_dcc0518232737c778d7b712de85b2ed5.perform(ra_action_performflowaction_dcc0518232737c778d7b712de85b2ed5.java:365)
 at com.pega.pegarules.session.internal.mgmt.Executable.doActivity(Executable.java:3500)
 at com.pega.pegarules.session.internal.mgmt.Executable.invokeActivity(Executable.java:10521)
 at com.pegarules.generated.activity.ra_action_finishassignment_d0045083e1b45f7e2330fe3464a87513.step10_circum0(ra_action_finishassignment_d0045083e1b45f7e2330fe3464a87513.java:1435)
 at com.pegarules.generated.activity.ra_action_finishassignment_d0045083e1b45f7e2330fe3464a87513.perform(ra_action_finishassignment_d0045083e1b45f7e2330fe3464a87513.java:229)
 at com.pega.pegarules.session.internal.mgmt.Executable.doActivity(Executable.java:3500)
 at com.pega.pegarules.session.internal.mgmt.base.ThreadRunner.runActivitiesAlt(ThreadRunner.java:646)
 at com.pega.pegarules.session.internal.mgmt.PRThreadImpl.runActivitiesAlt(PRThreadImpl.java:461)
 at com.pega.pegarules.session.internal.engineinterface.service.HttpAPI.runActivities(HttpAPI.java:3322)
 at com.pega.pegarules.session.external.engineinterface.service.EngineAPI.processRequestInner(EngineAPI.java:385)
 at sun.reflect.GeneratedMethodAccessor116.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
 at java.lang.reflect.Method.invoke(Method.java:611)
 at com.pega.pegarules.session.internal.PRSessionProviderImpl.performTargetActionWithLock(PRSessionProviderImpl.java:1270)
 at com.pega.pegarules.session.internal.PRSessionProviderImpl.doWithRequestorLocked(PRSessionProviderImpl.java:1008)
 at com.pega.pegarules.session.internal.PRSessionProviderImpl.doWithRequestorLocked(PRSessionProviderImpl.java:841)
 at com.pega.pegarules.session.external.engineinterface.service.EngineAPI.processRequest(EngineAPI.java:331)
 at com.pega.pegarules.session.internal.engineinterface.service.HttpAPI.invoke(HttpAPI.java:850)
 at com.pega.pegarules.session.internal.engineinterface.etier.impl.EngineImpl._invokeEngine_privact(EngineImpl.java:315)
 at com.pega.pegarules.session.internal.engineinterface.etier.impl.EngineImpl.invokeEngine(EngineImpl.java:263)
 at com.pega.pegarules.session.internal.engineinterface.etier.ejb.EngineBean.invokeEngine(EngineBean.java:225)
 at sun.reflect.GeneratedMethodAccessor90.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
 at java.lang.reflect.Method.invoke(Method.java:611)
 at com.pega.pegarules.internal.bootstrap.PRBootstrap.invokeMethod(PRBootstrap.java:367)
 at com.pega.pegarules.internal.bootstrap.PRBootstrap.invokeMethodPropagatingThrowable(PRBootstrap.java:408)
 at com.pega.pegarules.boot.internal.extbridge.AppServerBridgeToPega.invokeMethodPropagatingThrowable(AppServerBridgeToPega.java:223)
 at com.pega.pegarules.boot.internal.extbridge.AppServerBridgeToPega.invokeMethodPropagatingException(AppServerBridgeToPega.java:245)
 at com.pega.pegarules.internal.etier.ejb.EngineBeanBoot.invokeEngine(EngineBeanBoot.java:168)
 at com.pega.pegarules.internal.etier.interfaces.EJSLocalStatelessEngineBMT_f2439d86.invokeEngine(Unknown Source)
 at com.pega.pegarules.priv.context.JNDIEnvironment.invokeEngineInner(JNDIEnvironment.java:278)
 at com.pega.pegarules.priv.context.JNDIEnvironment.invokeEngine(JNDIEnvironment.java:223)
 at com.pega.pegarules.web.impl.WebStandardImpl.makeEtierRequest(WebStandardImpl.java:574)
 at com.pega.pegarules.web.impl.WebStandardImpl.doPost(WebStandardImpl.java:374)
 at sun.reflect.GeneratedMethodAccessor113.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
 at java.lang.reflect.Method.invoke(Method.java:611)
 at com.pega.pegarules.internal.bootstrap.PRBootstrap.invokeMethod(PRBootstrap.java:367)
 at com.pega.pegarules.internal.bootstrap.PRBootstrap.invokeMethodPropagatingThrowable(PRBootstrap.java:408)
 at com.pega.pegarules.boot.internal.extbridge.AppServerBridgeToPega.invokeMethodPropagatingThrowable(AppServerBridgeToPega.java:223)
 at com.pega.pegarules.boot.internal.extbridge.AppServerBridgeToPega.invokeMethod(AppServerBridgeToPega.java:272)
 at com.pega.pegarules.internal.web.servlet.WebStandardBoot.doPost(WebStandardBoot.java:121)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:595)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:668)
 at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1232)
 at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:781)
 at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:480)
 at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:178)
 at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1114)
 at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:87)
 at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:940)
 at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1817)
 at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:200)
 at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:463)
 at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:530)
 at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:316)
 at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:88)
 at com.ibm.ws.ssl.channel.impl.SSLReadServiceContext$SSLReadCompletedCallback.complete(SSLReadServiceContext.java:1818)
 at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:175)
 at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
 at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
 at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:138)
 at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:204)
 at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:775)
 at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:905)
 at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1881)
Caused by:
com.pega.pegarules.pub.clipboard.InvalidParameterException: cannot be null.  Details: Invalid value for aValue passed to com.pega.pegarules.data.internal.clipboard.ClipboardPropertyImpl.add()
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyBase.add(ClipboardPropertyBase.java:2447)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyBase.add(ClipboardPropertyBase.java:2442)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyBase.add(ClipboardPropertyBase.java:2438)
 at com.pega.pegarules.priv.integration.xml.ParseXMLSAXRuleWrapper.prPutAll(ParseXMLSAXRuleWrapper.java:3183)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.putAll(ClipboardPageImpl.java:2963)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.putAll(ClipboardPageImpl.java:2840)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.putAllAndReconcileRefProps(ClipboardPageImpl.java:2808)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageBase.putAll(ClipboardPageBase.java:1167)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.putAll(ClipboardPageImpl.java:482)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageBase.putAll(ClipboardPageBase.java:1163)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.putAll(ClipboardPageImpl.java:482)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.dissolveWrapperToClipboard(ClipboardPageImpl.java:4671)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.setAsSpecialJavaPage(ClipboardPageImpl.java:4627)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyImpl.addToList(ClipboardPropertyImpl.java:1488)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyImpl.addFromStorageForm(ClipboardPropertyImpl.java:4462)
 at com.pega.pegarules.data.internal.clipboard.DirectStreamContainerV7.addToClipboardObject(DirectStreamContainerV7.java:1025)
 at com.pega.pegarules.data.internal.clipboard.DirectStreamContainerV7.adoptList(DirectStreamContainerV7.java:518)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyImpl.expandStream(ClipboardPropertyImpl.java:2447)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyImpl.expandStream(ClipboardPropertyImpl.java:2378)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyBase.getListValues(ClipboardPropertyBase.java:2496)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyBase.size(ClipboardPropertyBase.java:1873)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.expandAll(ClipboardPageImpl.java:1165)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.expandAll(ClipboardPageImpl.java:1140)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.setAsSpecialJavaPage(ClipboardPageImpl.java:4608)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageBase.attachJavaObjectHelper(ClipboardPageBase.java:726)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.attachJavaObjectHelper(ClipboardPageImpl.java:482)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageBase.attachJavaObject(ClipboardPageBase.java:686)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.attachJavaObject(ClipboardPageImpl.java:482)
 at com.pega.pegarules.data.internal.clipboard.DirectStreamContainerV7.addToClipboardObject(DirectStreamContainerV7.java:989)
 at com.pega.pegarules.data.internal.clipboard.DirectStreamContainerV7.toPage(DirectStreamContainerV7.java:1143)
 at com.pega.pegarules.data.internal.clipboard.DirectStreamContainerV7.toPage(DirectStreamContainerV7.java:1150)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyImpl.expandStream(ClipboardPropertyImpl.java:2441)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyImpl.expandStream(ClipboardPropertyImpl.java:2378)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyImpl.resolveReferenceProperty(ClipboardPropertyImpl.java:5789)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyImpl.resolveReferenceProperty(ClipboardPropertyImpl.java:7709)
 at com.pega.pegarules.data.internal.clipboard.ClipboardPropertyImpl.adopt(ClipboardPropertyImpl.java:4571)
 at com.pega.pegarules.data.internal.clipboard.DirectStreamContainerV7.expandToProperty(DirectStreamContainerV7.java:728)
 ... 118 more