无法通过cloudformation更新任务定义

Question

当我以cloudformation更新堆栈以进行任务定义时，它将注销当前的活动任务定义，并且一次仅存在一个活动任务定义。

下面是代码：

AWSTemplateFormatVersion: 2010-09-09
Resources:
  TaskDefinition:
    Type: AWS::ECS::TaskDefinition
    Properties:
      RequiresCompatibilities: 
        - FARGATE         
      NetworkMode: awsvpc                       
      Cpu: 1024                       
      ExecutionRoleArn: "arn:aws:iam::XXXXXXXXXXXX:role/ecsTaskExecutionRole"
      Family: 'server1'
      Memory: 2048             
      ContainerDefinitions:
        -
          Name: nginx-container
          WorkingDirectory: '/var'
          Cpu: 256                 
          Memory: 512                     
          Essential: true
          Image: Nginx
          PortMappings:
            - ContainerPort: 80
          LogConfiguration:
            LogDriver: awslogs                
            Options:
              awslogs-group: sks-nginx   
              awslogs-region: us-west-2                  
              awslogs-stream-prefix: nginx-stream

先前的任务定义变为非活动状态，如何阻止先前的任务定义变为非活动状态。