Failed to locate a principal

org.kuali.rice.kew.exception.RouteManagerException: java.lang.IllegalArgumentException: Failed to locate a principal with principal name '26807785'
        at org.kuali.rice.kew.engine.StandardWorkflowEngine.process(StandardWorkflowEngine.java:156)
        at org.kuali.rice.kew.impl.document.DocumentProcessingQueueImpl.processWithOptions(DocumentProcessingQueueImpl.java:66)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        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.$Proxy159.processWithOptions(Unknown Source)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.kuali.rice.ksb.messaging.MessageServiceInvoker.invokeService(MessageServiceInvoker.java:157)
        at org.kuali.rice.ksb.messaging.MessageServiceInvoker$1.doInTransaction(MessageServiceInvoker.java:72)
        at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
        at org.kuali.rice.ksb.messaging.MessageServiceInvoker.run(MessageServiceInvoker.java:67)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
        at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.IllegalArgumentException: Failed to locate a principal with principal name '26807785'
        at org.kuali.rice.krad.UserSession.initPerson(UserSession.java:82)
        at org.kuali.rice.krad.UserSession.<init>(UserSession.java:70)
        at org.kuali.rice.krad.service.impl.DocumentServiceImpl.getByDocumentHeaderId(DocumentServiceImpl.java:674)
        at org.kuali.kfs.sys.document.workflow.SimpleBooleanSplitNode.process(SimpleBooleanSplitNode.java:41)
        at org.kuali.rice.kew.engine.transition.SplitTransitionEngine.isComplete(SplitTransitionEngine.java:37)
        at org.kuali.rice.kew.engine.StandardWorkflowEngine.processNodeInstance(StandardWorkflowEngine.java:183)
        at org.kuali.rice.kew.engine.StandardWorkflowEngine.process(StandardWorkflowEngine.java:146)
        ... 23 more