Workflow exception thrown during approval

• Type: Regression Bug
• Status: Closed
• Resolution: No Longer Reproducible
• Affects Version/s: 7.0.0 M3
• Fix Version/s: 7.0.0 M2
• Component/s: Workflow, Workflow > Administration
• Labels: None
• Fix Priority: 3

Steps to Reproduce:

1. Deploy Kaleo-web
2. Go to Admin > Control Panel > Workflow > Default Configuration
3. Configure Blogs Entry to "Single Approver (Version 1)" Workflow
4. Go to Site Administration > Content
5. Add Blog Entry > Submit for Publication
6. Go to Admin > Control Panel > Workflow > Submissions
7. Select Blogs Entry in "Pending" tab
8. Choose "Assign to Me"
9. Approve Task

Expect Result:
Workflow UI gives message that request has completed successfully

Actual Result:
Although the task is approved, Workflow UI throws error: "An Unexpected error occurred." And Console errors are thrown:

17:33:28,744 WARN  [http-bio-9080-exec-4][ProxyMessageListener:81] com.liferay.portal.kernel.workflow.WorkflowException: com.liferay.portal.kernel.workflow.WorkflowException: Cannot complete an already completed task 10750 for user 10202
com.liferay.portal.kernel.workflow.WorkflowException: com.liferay.portal.kernel.workflow.WorkflowException: Cannot complete an already completed task 10750 for user 10202
        at com.liferay.portal.workflow.kaleo.runtime.DefaultTaskManagerImpl.completeWorkflowTask(DefaultTaskManagerImpl.java:102)
        at sun.reflect.GeneratedMethodAccessor1513.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:320)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
        at com.liferay.portal.spring.transaction.DefaultTransactionExecutor.execute(DefaultTransactionExecutor.java:62)
        at com.liferay.portal.spring.transaction.TransactionInterceptor.invoke(TransactionInterceptor.java:55)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
        at com.sun.proxy.$Proxy453.completeWorkflowTask(Unknown Source)
        at sun.reflect.GeneratedMethodAccessor1513.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:320)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
        at com.liferay.portal.spring.transaction.TransactionInterceptor.invoke(TransactionInterceptor.java:52)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
        at com.sun.proxy.$Proxy454.completeWorkflowTask(Unknown Source)
        at com.liferay.portal.workflow.kaleo.WorkflowTaskManagerImpl.completeWorkflowTask(WorkflowTaskManagerImpl.java:110)
        at sun.reflect.GeneratedMethodAccessor1371.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:320)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
        at com.liferay.portal.spring.transaction.TransactionInterceptor.invoke(TransactionInterceptor.java:52)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
        at com.sun.proxy.$Proxy455.completeWorkflowTask(Unknown Source)
        at sun.reflect.GeneratedMethodAccessor1371.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:320)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
        at com.liferay.portal.spring.transaction.TransactionInterceptor.invoke(TransactionInterceptor.java:52)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
        at com.sun.proxy.$Proxy456.completeWorkflowTask(Unknown Source)
        at sun.reflect.GeneratedMethodAccessor1371.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at com.liferay.portal.kernel.messaging.proxy.ProxyRequest.execute(ProxyRequest.java:85)
        at com.liferay.portal.kernel.messaging.proxy.ProxyMessageListener.receive(ProxyMessageListener.java:51)
        at com.liferay.portal.kernel.messaging.InvokerMessageListener.receive(InvokerMessageListener.java:72)
        at com.liferay.portal.kernel.messaging.SynchronousDestination.send(SynchronousDestination.java:41)
        at com.liferay.portal.kernel.messaging.sender.DirectSynchronousMessageSender.send(DirectSynchronousMessageSender.java:54)
        at com.liferay.portal.kernel.messaging.sender.DefaultSingleDestinationSynchronousMessageSender.send(DefaultSingleDestinationSynchronousMessageSender.java:43)
        at com.liferay.portal.kernel.messaging.proxy.BaseProxyBean.synchronousSend(BaseProxyBean.java:51)
        at com.liferay.portal.messaging.proxy.MessagingProxyInvocationHandler.invoke(MessagingProxyInvocationHandler.java:47)
        at com.sun.proxy.$Proxy254.completeWorkflowTask(Unknown Source)
        at sun.reflect.GeneratedMethodAccessor1371.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:320)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
        at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:80)
        at com.liferay.portal.workflow.WorkflowPermissionAdvice.invoke(WorkflowPermissionAdvice.java:49)
        at sun.reflect.GeneratedMethodAccessor1161.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621)
        at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610)
        at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:65)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
        at com.sun.proxy.$Proxy255.completeWorkflowTask(Unknown Source)
        at com.liferay.portal.kernel.workflow.WorkflowTaskManagerUtil.completeWorkflowTask(WorkflowTaskManagerUtil.java:63)
        at com.liferay.portlet.workflowtasks.action.EditWorkflowTaskAction.completeTask(EditWorkflowTaskAction.java:160)
        at com.liferay.portlet.workflowtasks.action.EditWorkflowTaskAction.processAction(EditWorkflowTaskAction.java:66)
        at com.liferay.portal.struts.PortletRequestProcessor.process(PortletRequestProcessor.java:163)
        at com.liferay.portlet.StrutsPortlet.processAction(StrutsPortlet.java:216)
        at com.liferay.portlet.FilterChainImpl.doFilter(FilterChainImpl.java:71)
        at com.liferay.portlet.CheckboxParametersPortletFilter.doFilter(CheckboxParametersPortletFilter.java:56)
        at com.liferay.portlet.FilterChainImpl.doFilter(FilterChainImpl.java:68)
        at com.liferay.portal.kernel.portlet.PortletFilterUtil.doFilter(PortletFilterUtil.java:48)
        at com.liferay.portlet.InvokerPortletImpl.invoke(InvokerPortletImpl.java:605)
        at com.liferay.portlet.InvokerPortletImpl.invokeAction(InvokerPortletImpl.java:636)
        at com.liferay.portlet.InvokerPortletImpl.processAction(InvokerPortletImpl.java:316)
        at com.liferay.portlet.PortletContainerImpl._doProcessAction(PortletContainerImpl.java:410)
        at com.liferay.portlet.PortletContainerImpl.processAction(PortletContainerImpl.java:109)
        at com.liferay.portlet.SecurityPortletContainerWrapper.processAction(SecurityPortletContainerWrapper.java:108)
        at com.liferay.portlet.RestrictPortletContainerWrapper.processAction(RestrictPortletContainerWrapper.java:75)
        at com.liferay.portal.kernel.portlet.PortletContainerUtil.processAction(PortletContainerUtil.java:115)
        at com.liferay.portal.action.LayoutAction.processLayout(LayoutAction.java:377)
        at com.liferay.portal.action.LayoutAction.doExecute(LayoutAction.java:199)
        at com.liferay.portal.action.LayoutAction.execute(LayoutAction.java:91)
        at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
        at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
        at com.liferay.portal.struts.PortalRequestProcessor.process(PortalRequestProcessor.java:178)
        at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
        at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
        at com.liferay.portal.servlet.MainServlet.callParentService(MainServlet.java:544)
        at com.liferay.portal.servlet.MainServlet.service(MainServlet.java:521)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.secure.SecureFilter.processFilter(SecureFilter.java:293)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.jsoncontenttype.JSONContentTypeFilter.processFilter(JSONContentTypeFilter.java:42)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:97)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
        at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:487)
        at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:412)
        at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)
        at com.liferay.portal.servlet.FriendlyURLServlet.service(FriendlyURLServlet.java:156)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.strip.StripFilter.processFilter(StripFilter.java:360)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.gzip.GZipFilter.processFilter(GZipFilter.java:124)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.secure.SecureFilter.processFilter(SecureFilter.java:293)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.i18n.I18nFilter.processFilter(I18nFilter.java:243)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.etag.ETagFilter.processFilter(ETagFilter.java:86)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.jsoncontenttype.JSONContentTypeFilter.processFilter(JSONContentTypeFilter.java:42)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.autologin.AutoLoginFilter.processFilter(AutoLoginFilter.java:264)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.sso.ntlm.NtlmPostFilter.processFilter(NtlmPostFilter.java:83)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.sharepoint.SharepointFilter.processFilter(SharepointFilter.java:88)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:169)
        at com.liferay.portal.servlet.filters.virtualhost.VirtualHostFilter.processFilter(VirtualHostFilter.java:225)
        at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:59)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:185)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:96)
        at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:176)
        at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145)
        at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92)
        at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:394)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:165)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:96)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:165)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:96)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:185)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:96)
        at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:97)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
        at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
        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)
Caused by: com.liferay.portal.kernel.workflow.WorkflowException: Cannot complete an already completed task 10750 for user 10202
        at com.liferay.portal.workflow.kaleo.runtime.DefaultTaskManagerImpl.doCompleteWorkflowTask(DefaultTaskManagerImpl.java:227)
        at com.liferay.portal.workflow.kaleo.runtime.DefaultTaskManagerImpl.completeWorkflowTask(DefaultTaskManagerImpl.java:97)
        ... 216 more

Also occurs when using Single Approver on Web Content Article and Message Boards Thread