How to fix "Unable to locate package docker-compose-plugin" on Linux PC (Debian)

              ⭐ Summary

Why am I seeing “Unable to locate package docker-compose-plugin” when I try to start a Docker container? 

Because the Docker repository is not added on your system.

 Ubuntu/Debian’s default repos do not contain this package. Add Docker’s official repo, update apt, and the install will work. 

✅ Fix: Add Docker’s Official Repository (Required)

Run these exact commands in order:

1. Update apt + install prerequisites:

sudo apt-get update

sudo apt-get install -y ca-certificates curl gnupg

2. Add Docker’s GPG key:

sudo install -m 0755 -d /etc/apt/keyrings

curl -fsSL https://download.docker.com/linux/ubuntu/gpg \

  | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

sudo chmod a+r /etc/apt/keyrings/docker.gpg

3. Add the Docker repository:

echo \

"deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \

https://download.docker.com/linux/ubuntu \

$(. /etc/os-release && echo "$VERSION_CODENAME") stable" \

| sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

4. Update apt again + install the plugin:

sudo apt-get update

sudo apt-get install -y docker-compose-plugin

5. Verify:

docker compose version

           🧠 Why this happens

 The package only exists in Docker’s own repo, not Ubuntu/Debian’s defaults. If that repo isn’t added, apt simply can’t find it.