diff --git a/service/history/task/cross_cluster_source_task_executor.go b/service/history/task/cross_cluster_source_task_executor.go
index b1c2dba7505..059a9725411 100644
--- a/service/history/task/cross_cluster_source_task_executor.go
+++ b/service/history/task/cross_cluster_source_task_executor.go
@@ -257,6 +257,10 @@ func (t *crossClusterSourceTaskExecutor) executeCancelExecutionTask(
 
 		if failedCause != nil {
 			// remaining errors are non-retryable
+			cause := types.CancelExternalWorkflowExecutionFailedCauseUnknownExternalWorkflowExecution
+			if *failedCause == types.CrossClusterTaskFailedCauseWorkflowAlreadyCompleted {
+				cause = types.CancelExternalWorkflowExecutionFailedCauseWorkflowAlreadyCompleted
+			}
 			return requestCancelExternalExecutionFailed(
 				ctx,
 				taskInfo,
@@ -265,6 +269,7 @@ func (t *crossClusterSourceTaskExecutor) executeCancelExecutionTask(
 				taskInfo.TargetWorkflowID,
 				taskInfo.TargetRunID,
 				now,
+				cause,
 			)
 		}
 		return requestCancelExternalExecutionCompleted(
@@ -479,6 +484,10 @@ func (t *crossClusterSourceTaskExecutor) executeSignalExecutionTask(
 
 		if failedCause != nil {
 			// remaining errors are non-retryable
+			cause := types.SignalExternalWorkflowExecutionFailedCauseUnknownExternalWorkflowExecution
+			if *failedCause == types.CrossClusterTaskFailedCauseWorkflowAlreadyCompleted {
+				cause = types.SignalExternalWorkflowExecutionFailedCauseWorkflowAlreadyCompleted
+			}
 			return signalExternalExecutionFailed(
 				ctx,
 				taskInfo,
@@ -488,6 +497,7 @@ func (t *crossClusterSourceTaskExecutor) executeSignalExecutionTask(
 				taskInfo.TargetRunID,
 				signalInfo.Control,
 				now,
+				cause,
 			)
 		}
 
diff --git a/service/history/task/cross_cluster_source_task_executor_test.go b/service/history/task/cross_cluster_source_task_executor_test.go
index 916e962d9ee..78b7afa01b9 100644
--- a/service/history/task/cross_cluster_source_task_executor_test.go
+++ b/service/history/task/cross_cluster_source_task_executor_test.go
@@ -664,7 +664,7 @@ func (s *crossClusterSourceTaskExecutorSuite) TestExecuteCancelExecution_Failure
 		&types.CrossClusterTaskResponse{
 			TaskType:    types.CrossClusterTaskTypeCancelExecution.Ptr(),
 			TaskState:   int16(processingStateInitialized),
-			FailedCause: types.CrossClusterTaskFailedCauseWorkflowNotExists.Ptr(),
+			FailedCause: types.CrossClusterTaskFailedCauseWorkflowAlreadyCompleted.Ptr(),
 		},
 		func(
 			mutableState execution.MutableState,
diff --git a/service/history/task/transfer_active_task_executor.go b/service/history/task/transfer_active_task_executor.go
index 802bbd646c6..f5babe3a49f 100644
--- a/service/history/task/transfer_active_task_executor.go
+++ b/service/history/task/transfer_active_task_executor.go
@@ -630,6 +630,7 @@ func (t *transferActiveTaskExecutor) processCancelExecution(
 			task.TargetWorkflowID,
 			task.TargetRunID,
 			t.shard.GetTimeSource().Now(),
+			types.CancelExternalWorkflowExecutionFailedCauseUnknownExternalWorkflowExecution,
 		)
 		return err
 	}
@@ -656,6 +657,11 @@ func (t *transferActiveTaskExecutor) processCancelExecution(
 			// for retryable error just return
 			return err
 		}
+		cause := types.CancelExternalWorkflowExecutionFailedCauseUnknownExternalWorkflowExecution
+		var alreadyCompletedErr *types.WorkflowExecutionAlreadyCompletedError
+		if errors.As(err, &alreadyCompletedErr) {
+			cause = types.CancelExternalWorkflowExecutionFailedCauseWorkflowAlreadyCompleted
+		}
 		return requestCancelExternalExecutionFailed(
 			ctx,
 			task,
@@ -664,6 +670,7 @@ func (t *transferActiveTaskExecutor) processCancelExecution(
 			task.TargetWorkflowID,
 			task.TargetRunID,
 			t.shard.GetTimeSource().Now(),
+			cause,
 		)
 	}
 
@@ -750,6 +757,7 @@ func (t *transferActiveTaskExecutor) processSignalExecution(
 			task.TargetRunID,
 			signalInfo.Control,
 			t.shard.GetTimeSource().Now(),
+			types.SignalExternalWorkflowExecutionFailedCauseUnknownExternalWorkflowExecution,
 		)
 	}
 
@@ -769,12 +777,17 @@ func (t *transferActiveTaskExecutor) processSignalExecution(
 			tag.TargetWorkflowRunID(task.TargetRunID),
 			tag.Error(err))
 
-		// Check to see if the error is non-transient, in which case add SignalFailed
+		// Check to see if the error is non-transient, in which case add RequestCancelFailed
 		// event and complete transfer task by setting the err = nil
 		if common.IsServiceTransientError(err) || common.IsContextTimeoutError(err) {
 			// for retryable error just return
 			return err
 		}
+		var alreadyCompletedErr *types.WorkflowExecutionAlreadyCompletedError
+		cause := types.SignalExternalWorkflowExecutionFailedCauseUnknownExternalWorkflowExecution
+		if errors.As(err, &alreadyCompletedErr) {
+			cause = types.SignalExternalWorkflowExecutionFailedCauseWorkflowAlreadyCompleted
+		}
 		return signalExternalExecutionFailed(
 			ctx,
 			task,
@@ -784,6 +797,7 @@ func (t *transferActiveTaskExecutor) processSignalExecution(
 			task.TargetRunID,
 			signalInfo.Control,
 			t.shard.GetTimeSource().Now(),
+			cause,
 		)
 	}
 
@@ -1419,6 +1433,7 @@ func requestCancelExternalExecutionFailed(
 	targetWorkflowID string,
 	targetRunID string,
 	now time.Time,
+	cause types.CancelExternalWorkflowExecutionFailedCause,
 ) error {
 
 	err := updateWorkflowExecution(ctx, wfContext, true,
@@ -1439,7 +1454,7 @@ func requestCancelExternalExecutionFailed(
 				targetDomain,
 				targetWorkflowID,
 				targetRunID,
-				types.CancelExternalWorkflowExecutionFailedCauseUnknownExternalWorkflowExecution,
+				cause,
 			)
 			return err
 		},
@@ -1464,6 +1479,7 @@ func signalExternalExecutionFailed(
 	targetRunID string,
 	control []byte,
 	now time.Time,
+	cause types.SignalExternalWorkflowExecutionFailedCause,
 ) error {
 
 	err := updateWorkflowExecution(ctx, wfContext, true,
@@ -1485,7 +1501,7 @@ func signalExternalExecutionFailed(
 				targetWorkflowID,
 				targetRunID,
 				control,
-				types.SignalExternalWorkflowExecutionFailedCauseUnknownExternalWorkflowExecution,
+				cause,
 			)
 			return err
 		},
diff --git a/service/history/task/transfer_active_task_executor_test.go b/service/history/task/transfer_active_task_executor_test.go
index 3d8e54a3fb6..c4f81196eb1 100644
--- a/service/history/task/transfer_active_task_executor_test.go
+++ b/service/history/task/transfer_active_task_executor_test.go
@@ -1046,7 +1046,7 @@ func (s *transferActiveTaskExecutorSuite) TestProcessCancelExecution_Success() {
 	)
 }
 
-func (s *transferActiveTaskExecutorSuite) TestProcessCancelExecution_Failure() {
+func (s *transferActiveTaskExecutorSuite) TestProcessCancelExecution_EntityNotExistsError() {
 	s.testProcessCancelExecution(
 		s.targetDomainID,
 		func(
@@ -1067,6 +1067,27 @@ func (s *transferActiveTaskExecutorSuite) TestProcessCancelExecution_Failure() {
 	)
 }
 
+func (s *transferActiveTaskExecutorSuite) TestProcessCancelExecution_WorkflowAlreadyCompleted() {
+	s.testProcessCancelExecution(
+		s.targetDomainID,
+		func(
+			mutableState execution.MutableState,
+			workflowExecution, targetExecution types.WorkflowExecution,
+			event *types.HistoryEvent,
+			transferTask Task,
+			requestCancelInfo *persistence.RequestCancelInfo,
+		) {
+			persistenceMutableState, err := test.CreatePersistenceMutableState(mutableState, event.ID, event.Version)
+			s.NoError(err)
+			s.mockExecutionMgr.On("GetWorkflowExecution", mock.Anything, mock.Anything).Return(&persistence.GetWorkflowExecutionResponse{State: persistenceMutableState}, nil)
+			cancelRequest := createTestRequestCancelWorkflowExecutionRequest(s.targetDomainName, transferTask.GetInfo().(*persistence.TransferTaskInfo), requestCancelInfo.CancelRequestID)
+			s.mockHistoryClient.EXPECT().RequestCancelWorkflowExecution(gomock.Any(), cancelRequest).Return(&types.WorkflowExecutionAlreadyCompletedError{}).Times(1)
+			s.mockHistoryV2Mgr.On("AppendHistoryNodes", mock.Anything, mock.Anything).Return(&persistence.AppendHistoryNodesResponse{}, nil).Once()
+			s.mockExecutionMgr.On("UpdateWorkflowExecution", mock.Anything, mock.Anything).Return(&persistence.UpdateWorkflowExecutionResponse{MutableStateUpdateSessionStats: &persistence.MutableStateUpdateSessionStats{}}, nil).Once()
+		},
+	)
+}
+
 func (s *transferActiveTaskExecutorSuite) TestProcessCancelExecution_Duplication() {
 	s.testProcessCancelExecution(
 		s.targetDomainID,
@@ -1202,7 +1223,7 @@ func (s *transferActiveTaskExecutorSuite) TestProcessSignalExecution_Success() {
 	)
 }
 
-func (s *transferActiveTaskExecutorSuite) TestProcessSignalExecution_Failure() {
+func (s *transferActiveTaskExecutorSuite) TestProcessSignalExecution_EntityNotExistsError() {
 	s.testProcessSignalExecution(
 		s.targetDomainID,
 		func(
@@ -1223,6 +1244,26 @@ func (s *transferActiveTaskExecutorSuite) TestProcessSignalExecution_Failure() {
 	)
 }
 
+func (s *transferActiveTaskExecutorSuite) TestProcessSignalExecution_WorkflowAlreadyCompletedError() {
+	s.testProcessSignalExecution(
+		s.targetDomainID,
+		func(
+			mutableState execution.MutableState,
+			workflowExecution, targetExecution types.WorkflowExecution,
+			event *types.HistoryEvent,
+			transferTask Task,
+			signalInfo *persistence.SignalInfo,
+		) {
+			persistenceMutableState, err := test.CreatePersistenceMutableState(mutableState, event.ID, event.Version)
+			s.NoError(err)
+			s.mockExecutionMgr.On("GetWorkflowExecution", mock.Anything, mock.Anything).Return(&persistence.GetWorkflowExecutionResponse{State: persistenceMutableState}, nil)
+			signalRequest := createTestSignalWorkflowExecutionRequest(s.targetDomainName, transferTask.GetInfo().(*persistence.TransferTaskInfo), signalInfo)
+			s.mockHistoryClient.EXPECT().SignalWorkflowExecution(gomock.Any(), signalRequest).Return(&types.WorkflowExecutionAlreadyCompletedError{}).Times(1)
+			s.mockHistoryV2Mgr.On("AppendHistoryNodes", mock.Anything, mock.Anything).Return(&persistence.AppendHistoryNodesResponse{}, nil).Once()
+			s.mockExecutionMgr.On("UpdateWorkflowExecution", mock.Anything, mock.Anything).Return(&persistence.UpdateWorkflowExecutionResponse{MutableStateUpdateSessionStats: &persistence.MutableStateUpdateSessionStats{}}, nil).Once()
+		},
+	)
+}
 func (s *transferActiveTaskExecutorSuite) TestProcessSignalExecution_Duplication() {
 	s.testProcessSignalExecution(
 		s.targetDomainID,