ERROR: Version in "./docker-compose.yml" is unsupported.

[kirantpatil]

I followed your steps but got the below error.

$ docker --version
Docker version 20.10.21, build 20.10.21-0ubuntu1~20.04.2

$ docker-compose up
ERROR: Version in "./docker-compose.yml" is unsupported. You might be seeing this error because you're using the wrong Compose file version. Either specify a supported version (e.g "2.2" or "3.3") and place your service definitions under the `services` key, or omit the `version` key and place your service definitions at the root of the file to use version 1.
For more on the Compose file format versions, see https://docs.docker.com/compose/compose-file/