Trying to find cause of below exception, when SOAP service (authenticated) called from client application with correct user name and password. But got this error. This is happened only once and not seeing any more.

Verified the password violation report and security policies, it looks good.

Any thoughts which scenario this might have occurred?

Exception Details :

2016-02-29 14:10:37,133 [    WebContainer : 7] [  STANDARD] [rv-Headless:04.47.64] (  internal.services.ServiceAPI) ERROR lnptegpapp33.tsysecom.org|XX.XX.XX.XX|SOAP|HeadlessCallCenter|CAInCorrInteraction|CreateNewWork|AE3734B4668B272F026463FE17C98E9B3  - SOAP service [ServPkName][OperationName][CreateNewWork] failed:Service requestor could not be authenticated:com.pega.pegarules.pub.services.ServiceException: Service requestor could not be authenticated

                at com.pega.pegarules.integration.engine.internal.services.ServiceAPI.handleAuthentication(ServiceAPI.java:1597)

                at com.pega.pegarules.session.external.engineinterface.service.EngineAPI.activityExecutionProlog(EngineAPI.java:548)

                at com.pega.pegarules.session.external.engineinterface.service.EngineAPI.processRequestInner(EngineAPI.java:383)

                at sun.reflect.GeneratedMethodAccessor132.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.integration.engine.internal.services.soap.SOAPService.invoke(SOAPService.java:579)

                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.GeneratedMethodAccessor83.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.GeneratedMethodAccessor127.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:1227)

                at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:776)

                at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:458)

                at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:178)

                at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1032)

                at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:3761)

                at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:304)

                at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:976)

                at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1662)

                at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:200)

                at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:459)

                at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:526)

                at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:312)

                at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:283)

                at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:214)

                at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:113)

                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$1.run(AsyncChannelFuture.java:205)

                at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1862)

Caused by: com.pega.pegarules.pub.clipboard.ReadOnlyException: The page or property Declare_AuthPolicies.pySourcePage is read-only, and cannot be modified.  Calling method: com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.putString(String, String)  Details: (none)

                at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.putStringOverride(ClipboardPageImpl.java:2675)

                at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.putStringOverride(ClipboardPageImpl.java:2600)

                at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.putString(ClipboardPageImpl.java:2584)

                at com.pega.pegarules.data.internal.clipboard.ClipboardPageImpl.putString(ClipboardPageImpl.java:2580)

                at com.pega.pegarules.exec.internal.declare.infengine.pages.DeclarativePageDirectoryImpl.populateSourceInformation(DeclarativePageDirectoryImpl.java:621)

                at com.pega.pegarules.exec.internal.declare.infengine.pages.DeclarativePageDirectoryImpl.runLoadActivity(DeclarativePageDirectoryImpl.java:557)

                at com.pega.pegarules.session.internal.mgmt.base.handler.ReadOnlyDataPageHandler.loadDataPage(ReadOnlyDataPageHandler.java:232)

                at com.pega.pegarules.session.internal.mgmt.base.handler.ReadOnlyDataPageHandler.findDataPage(ReadOnlyDataPageHandler.java:435)

                at com.pega.pegarules.session.internal.mgmt.base.AbstractPageDirectory.findDataPageInCurrentDir(AbstractPageDirectory.java:920)

                at com.pega.pegarules.session.internal.mgmt.base.AbstractPageDirectory.getDirectPage(AbstractPageDirectory.java:713)

                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.pega.pegarules.session.internal.mgmt.Executable.findPage(Executable.java:2016)

                at com.pega.pegarules.session.internal.mgmt.authentication.Authentication.getSecuritySettingDeclarePage(Authentication.java:652)

                at com.pega.pegarules.session.internal.mgmt.authentication.Authentication.getSecuritySettingAsBoolean(Authentication.java:661)

                at com.pega.pegarules.session.internal.mgmt.authentication.Authentication.doAuthentication(Authentication.java:441)

                at com.pega.pegarules.integration.engine.internal.services.ServiceAPI.handleAuthentication(ServiceAPI.java:1577)

                ... 56 more