Failed to start dchpd.service: Unit not found.

根据提供的引用内容，你遇到的问题是Failed to start docker.service: Unit not found。这个错误通常是由于docker服务没有正确安装或者启动导致的。为了解决这个问题，你可以尝试几个步骤：

1.检查docker服务是否已经正确安装。你可以使用以下命令来检查docker服务是否已经正确安装：

sudo systemctl status docker.service

如果docker服务已经正确安装，你应该会看到类似于以下内容的输出：

● docker.service - Docker Application Container Engine
   Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2021-08-10 14:20:20 UTC; 1 weeks 0 days ago
     Docs: https://docs.docker.com
 Main PID: 1234 (dockerd)
    Tasks: 10
   Memory: 46.3M
      CPU: 1.234s
   CGroup: /system.slice/docker.service
           ├─1234 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
           └─5678 containerd --config /var/run/docker/containerd/containerd.toml --log-level info

Aug 10 14:20:20 ubuntu systemd[1]: Starting Docker Application Container Engine...
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="Starting up"
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="detected 127.0.0.53 nameserver, assuming systemd-resolved, so using resolv.conf: /run/systemd/resolve/resolv.conf"
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="parsed scheme: \"unix\""
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="scheme \"unix\" not registered, fallback to default scheme"
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="ccResolverWrapper: sending new addresses to cc: [{unix:///run/containerd/containerd.sock 0  <nil>}]
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="ClientConn switching balancer to \"pick_first\""
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="parsed scheme: \"unix\""
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="scheme \"unix\" not registered, fallback to default scheme"
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="ccResolverWrapper: sending new addresses to cc: [{unix:///run/containerd/containerd.sock 0  <nil>}]
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="ClientConn switching balancer to \"pick_first\""
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="Loading containers: start."
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="Loading containers: done."
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="Docker daemon" commit="abcdefg" graphdriver(s)="overlay2" version=20.10.7
Aug 10 14:20:20 ubuntu dockerd[1234]: time="2021-08-10T14:20:20.123456789Z" level=info msg="Daemon has completed initialization"
Aug 10 14:20:20 ubuntu systemd[1]: Started Docker Application Container Engine.

如果docker服务没有正确安装，你应该会看到类似于以下内容的输出：

● docker.service
   Loaded: not-found (Reason: No such file or directory)
   Active: inactive (dead)

2.如果docker服务没有正确安装，你可以尝试重新安装docker服务。你可以使用以下命令来重新安装docker服务：

sudo apt-get update
sudo apt-get install docker.io

3.如果docker服务已经正确安装，但是仍然无法启动，你可以尝试重新启动docker服务。你可以使用以下命令来重新启动docker服务：

sudo systemctl restart docker.service