invalid (null) workflowUser

java.lang.IllegalArgumentException: invalid (null) workflowUser
    at org.kuali.rice.krad.workflow.service.impl.WorkflowDocumentServiceImpl.loadWorkflowDocument(WorkflowDocumentServiceImpl.java:109)
    at sun.reflect.GeneratedMethodAccessor926.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:318)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
    at com.sun.proxy.$Proxy103.loadWorkflowDocument(Unknown Source)
    at org.kuali.rice.krad.service.impl.DocumentServiceImpl.getByDocumentHeaderIdSessionless(DocumentServiceImpl.java:718)
    at org.kuali.rice.krad.workflow.attribute.DataDictionarySearchableAttribute.extractDocumentAttributes(DataDictionarySearchableAttribute.java:95)
    at org.kuali.kfs.sys.document.workflow.FinancialSystemSearchableAttribute.extractDocumentAttributes(FinancialSystemSearchableAttribute.java:185)
    at org.kuali.kfs.sys.document.workflow.KFSDocumentSearchCustomizer.extractDocumentAttributes(KFSDocumentSearchCustomizer.java:75)
    at org.kuali.rice.kew.impl.document.attribute.DocumentAttributeIndexingQueueImpl.buildSearchableAttributeValues(DocumentAttributeIndexingQueueImpl.java:105)
    at org.kuali.rice.kew.impl.document.attribute.DocumentAttributeIndexingQueueImpl.indexDocument(DocumentAttributeIndexingQueueImpl.java:78)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:318)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
    at com.sun.proxy.$Proxy185.indexDocument(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.kuali.rice.ksb.messaging.MessageServiceInvoker.invokeService(MessageServiceInvoker.java:157)
    at org.kuali.rice.ksb.messaging.MessageServiceInvoker$1.doInTransaction(MessageServiceInvoker.java:72)
    at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
    at org.kuali.rice.ksb.messaging.MessageServiceInvoker.run(MessageServiceInvoker.java:67)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)