Docker Compose: 'docker-compose: command not found' after upgrading Docker, or the warning 'the attribute version is obsolete, it will be ignored'. How do I move to Compose v2?

Cause: Docker Compose v1 (the Python 'docker-compose' command) stopped receiving updates in 2023 and is no longer shipped with current Docker Desktop or Docker Engine packages. Compose v2 is a Docker CLI plugin, so the command is 'docker compose' (a space, not a hyphen). Scripts, CI jobs, Makefiles and older tutorials that call docker-compose then fail with 'command not found'. Separately, Compose v2 follows the Compose Specification, where the top-level 'version:' field is obsolete; v2 ignores it and prints the warning. Fix: 1. Use the v2 command: replace docker-compose with docker compose in scripts and CI. Check it's installed with docker compose version. On Linux without Docker Desktop, install the docker-compose-plugin package from Docker's repository. 2. If you can't change many scripts at once, a temporary shell alias or wrapper (docker-compose -> docker compose) works, but update scripts over time. 3. Remove the 'version: "3.x"' line from compose.yaml / docker-compose.yml to silence the warning; it no longer selects a file format. Both file names are still read; compose.yaml is the preferred name. 4. Check for behavior differences Docker documents in the v1-to-v2 migration guide: container names use hyphens instead of underscores by default (project-service-1), and some old flags changed. Update anything that parses container names. 5. In CI images, use a current docker:cli or runner image that includes the compose plugin rather than pip install docker-compose. Verify: docker compose version prints v2.x, and docker compose config renders your file without warnings. Sources: https://docs.docker.com/compose/releases/migrate/ https://docs.docker.com/reference/compose-file/version-and-name/