为什么Docker容器更新不稳定？

我使用命令docker container update --cpus 1 target_container来更新。但是在大多数情况不起作用，返回“you must provide one or more flags when using this command”，但是它确实起作用

有人知道原因吗？

相关日志：

$ docker container update --cpus 0.5 target_container
you must provide one or more flags when using this command
$ docker container update --cpus 0.5 target_container
you must provide one or more flags when using this command
$ docker container update --cpus 0.5 target_container
target_container

docker的版本是：

Client:
 Version:           18.09.7
 API version:       1.39
 Go version:        go1.10.4
 Git commit:        2d0083d
 Built:             Fri Aug 16 14:19:38 2019
 OS/Arch:           linux/amd64
 Experimental:      false

Server:
 Engine:
  Version:          18.09.7
  API version:      1.39 (minimum version 1.12)
  Go version:       go1.10.4
  Git commit:       2d0083d
  Built:            Thu Aug 15 15:12:41 2019
  OS/Arch:          linux/amd64
  Experimental:     false