Docker error: port is already allocated

Where is the port allocated?

I got an error message when I tried docker compose up.

docker compose up
Attaching to app-1
Gracefully stopping... (press Ctrl+C again to force)
Error response from daemon: driver failed programming external connectivity on endpoint hyunphoto-cbv-app-1 (876c605de16e8d99e9e1b806de): Bind for 0.0.0.0:8000 failed: port is already allocated

What did I do before?
I remembered that I had run a project on Docker earlier. That could be cause. Then, how we could check it?

I checked by two steps.
First. Command docker compose down what I ran the project before. I could get the info which container is still running.

! Network hyunphoto-fbv_default  Resource is still in use                                            0.0s 

Second. Command docker network inspect hyunphoto-fbv_default.

[
    {
        "Name": "hyunphoto-fbv_default",
        "Id": "eee2041694529e233c352c6e314",
        "Created": "2024-11-15T14:15:07.24638069Z",
        "Scope": "local", # this network works only in local.
        "Driver": "bridge", # Docker network type. 
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": [
                {
                    "Subnet": "172.20.0.0/16", # IP address of this network.
                    "Gateway": "172.20.0.1" # Gateway IP of this network.
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": { # This container is running.
            "20ea5e895019ac3279ce5009a6": {
                "Name": "hyunphoto-fbv-proxy-1", 
                "EndpointID": "5b86698bc46027072001506a1cd",
                "MacAddress": "02:42:ac:14:00:04", # Mac address allocated to the network interface of a container.
                "IPv4Address": "172.20.0.4/16", # IPv4 address allocated to a container.
                "IPv6Address": ""
            }
        },
        "Options": {},
        "Labels": {
            "com.docker.compose.network": "default", 
            "com.docker.compose.project": "hyunphoto-fbv", # Docker compose project name to which this network belongs.
            "com.docker.compose.version": "2.29.2" # Docker Compose version that created the network.
        }
    }
]

Now I know the container that I have to stop.
Solution.

docker stop hyunphoto-fbv-proxy-1

And I can see there is no a container.

apple@GH-MacBook-Pro hyunphoto-fbv % docker network inspect hyunphoto-fbv_default

[
    {
        "Name": "hyunphoto-fbv_default",
        "Id": "eee2041694529e233c352c6e3140aee457c6a33b468b92a33327fd1d39dff5bf",
        "Created": "2024-11-15T14:15:07.24638069Z",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": [
                {
                    "Subnet": "172.20.0.0/16",
                    "Gateway": "172.20.0.1"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {}, # HERE!
        "Options": {},
        "Labels": {
            "com.docker.compose.network": "default",
            "com.docker.compose.project": "hyunphoto-fbv",
            "com.docker.compose.version": "2.29.2"
        }
    }
]