diff --git a/service/frontend/workflowHandler.go b/service/frontend/workflowHandler.go
index 3ff013e03f9..a34fee70e3a 100644
--- a/service/frontend/workflowHandler.go
+++ b/service/frontend/workflowHandler.go
@@ -959,6 +959,10 @@ func (wh *WorkflowHandler) RespondWorkflowTaskCompleted(
 		return nil, errRequestNotSet
 	}
 
+	if len(request.GetIdentity()) > wh.config.MaxIDLengthLimit() {
+		return nil, errIdentityTooLong
+	}
+
 	taskToken, err := wh.tokenSerializer.Deserialize(request.TaskToken)
 	if err != nil {
 		return nil, err
@@ -973,10 +977,6 @@ func (wh *WorkflowHandler) RespondWorkflowTaskCompleted(
 		return nil, err
 	}
 
-	if len(request.GetIdentity()) > wh.config.MaxIDLengthLimit() {
-		return nil, errIdentityTooLong
-	}
-
 	completedResp := &workflowservice.RespondWorkflowTaskCompletedResponse{}
 	if request.GetReturnNewWorkflowTask() && histResp != nil && histResp.StartedResponse != nil {
 		taskToken := &tokenspb.Task{
diff --git a/service/history/workflow/mutable_state_impl.go b/service/history/workflow/mutable_state_impl.go
index 6b96eac4206..a641362b969 100644
--- a/service/history/workflow/mutable_state_impl.go
+++ b/service/history/workflow/mutable_state_impl.go
@@ -3236,7 +3236,15 @@ func (e *MutableStateImpl) ReplicateChildWorkflowExecutionStartedEvent(
 	attributes := event.GetChildWorkflowExecutionStartedEventAttributes()
 	initiatedID := attributes.GetInitiatedEventId()
 
-	ci, _ := e.GetChildExecutionInfo(initiatedID)
+	ci, ok := e.GetChildExecutionInfo(initiatedID)
+	if !ok {
+		e.logError(
+			fmt.Sprintf("unable to find child workflow event ID: %v in mutable state", initiatedID),
+			tag.ErrorTypeInvalidMutableStateAction,
+		)
+		return ErrMissingChildWorkflowInfo
+	}
+
 	ci.StartedId = event.GetEventId()
 	ci.StartedRunId = attributes.GetWorkflowExecution().GetRunId()
 	e.updateChildExecutionInfos[ci.InitiatedId] = ci