this looks like there is no web service application deployed to Tomcat/EWS and this operation that invokes Web Service fails and stays in Troubleshoot task instead of moving to Appraisal.

Taken from the logs the Tomcat deploys applications - as you can see there is no ws app:

INFO: Deployment of web application directory /home/hudson/hudson_workspace/workspace/BxMS/BxMS-prod-6.3/business-central/Process_Management/all/bpms-prod-6.3-business-central-bigapp-rhel-ews2/jboss-ews-2.1/tomcat7/webapps/business-central has finished in 55,617 ms
Apr 18, 2016 6:51:14 AM org.apache.catalina.startup.HostConfig deployDirectory
INFO: Deploying web application directory /home/hudson/hudson_workspace/workspace/BxMS/BxMS-prod-6.3/business-central/Process_Management/all/bpms-prod-6.3-business-central-bigapp-rhel-ews2/jboss-ews-2.1/tomcat7/webapps/examples
Apr 18, 2016 6:51:14 AM org.apache.catalina.startup.HostConfig deployDirectory
INFO: Deployment of web application directory /home/hudson/hudson_workspace/workspace/BxMS/BxMS-prod-6.3/business-central/Process_Management/all/bpms-prod-6.3-business-central-bigapp-rhel-ews2/jboss-ews-2.1/tomcat7/webapps/examples has finished in 270 ms
Apr 18, 2016 6:51:14 AM org.apache.catalina.startup.HostConfig deployDirectory
INFO: Deploying web application directory /home/hudson/hudson_workspace/workspace/BxMS/BxMS-prod-6.3/business-central/Process_Management/all/bpms-prod-6.3-business-central-bigapp-rhel-ews2/jboss-ews-2.1/tomcat7/webapps/host-manager
Apr 18, 2016 6:51:14 AM org.apache.catalina.startup.HostConfig deployDirectory
INFO: Deployment of web application directory /home/hudson/hudson_workspace/workspace/BxMS/BxMS-prod-6.3/business-central/Process_Management/all/bpms-prod-6.3-business-central-bigapp-rhel-ews2/jboss-ews-2.1/tomcat7/webapps/host-manager has finished in 306 ms

moreover when you look at the execution of the process you can see following 

2016-04-18 07:00:32,443 [http-bio-8080-exec-40] WARN  org.jbpm.process.audit.VariableInstanceLog- Variable content was trimmed as it was too long (more than 255 characters)
2016-04-18 07:00:32,444 [http-bio-8080-exec-40] WARN  org.jbpm.process.audit.VariableInstanceLog- Variable content was trimmed as it was too long (more than 255 characters)
2016-04-18 07:00:32,459 [http-bio-8080-exec-40] WARN  org.jbpm.services.task.audit.impl.model.TaskVariableImpl- Task variable 'errorStack' content was trimmed as it was too long (more than 4000 characters)

which indicate WS call failed and process instance moved to troubleshoot user task

So I'd like to suggest to deploy the mertgage-ws-demo application (https://github.com/jboss-integration/jboss-bpm-example-app/blob/master/mortgage-demo-ws/pom.xml) to make sure it can be reached from within process instance.

1) General info: why was this reported only now?
Until ER3 the full testing of BigApp on ews was blocked by bug #1320206.
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2) I definitely don't consider this BZ as blocker for 6.3 release as it only affects bpm-example app on JWS2/3. The readme instructions for this app explicitely mention that it is to be tried on EAP.
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3) @Maciej if you check the beginning of the attached catalina.out you can see, that the required mortgage-demo-ws is in fact deployed so this should not be an issue.

INFO: Deployment of web application directory /home/hudson/hudson_workspace/workspace/BxMS/BxMS-prod-6.3/business-central/Process_Management/all/bpms-prod-6.3-business-central-bigapp-rhel-ews2/jboss-ews-2.1/tomcat7/webapps/jboss-mortgage-demo-ws has finished in 529 ms

I tried to reproduce this locally but failed with some jsp exceptions from form modeler when trying to open task forms in task list. We'll have to investigate this some more and find out what's happening.

Investigated this a bit further and found the following.
Even thought there is a message in catalina.out showing that the jboss-mortgage-demo-ws was deployed, the webservice itself does not work and the following stacktrace (see below) appears in the Troubleshoot human task from the MortgageApplication process.

Also when visiting http://localhost:8080/jboss-mortgage-demo-ws/CreditService?wsdl it returns HTTP 404

We believe it is caused by the fact that this is a SOAP web service which is not supported on tomcat by default, because it's missing JAX-WS libraries.

Now the question is: do we want to complicate this demo app and its setup process by including instructions on how to make it work on JWS or do we rather want to restrict the demo to be EAP only? I would strongly recommend we go for the later :-)
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org.apache.cxf.service.factory.ServiceConstructionException: Failed to create service.
	at org.apache.cxf.wsdl11.WSDLServiceFactory.<init>(WSDLServiceFactory.java:100)
	at org.apache.cxf.endpoint.dynamic.DynamicClientFactory.createClient(DynamicClientFactory.java:295)
	at org.apache.cxf.endpoint.dynamic.DynamicClientFactory.createClient(DynamicClientFactory.java:240)
	at org.jbpm.process.workitem.webservice.WebServiceWorkItemHandler.getWSClient(WebServiceWorkItemHandler.java:201)
	at org.jbpm.process.workitem.webservice.WebServiceWorkItemHandler.executeWorkItem(WebServiceWorkItemHandler.java:105)
	at org.drools.persistence.jpa.processinstance.JPAWorkItemManager.internalExecuteWorkItem(JPAWorkItemManager.java:69)
	at org.jbpm.workflow.instance.node.WorkItemNodeInstance.internalTrigger(WorkItemNodeInstance.java:138)

Jan,

thanks for further investigation. I agree with you that (at least for now) we should not support this example on tomcat as it can't deploy JAX-WS application out of the box.

So I opt for closing this as won't fix