Docker Compose "Additional property X is not allowed" in CI

Compose validated your file against its schema and found a key it does not recognize at that position. Usually a typo (enviroment), a wrong nesting level, or a key that belongs elsewhere.

What this error means

A docker compose up/config fails with services.<name> Additional property <key> is not allowed. The file parses as YAML but violates the Compose schema at the named key.

docker compose output

services.web Additional property buld is not allowed
# "buld" is a typo for "build"; the schema has no "buld" key

Common causes

A misspelled key

Typos like buld, enviroment, volums, or command_line are not in the schema, so Compose reports them as disallowed additional properties.

A key at the wrong nesting level

A valid key placed under the wrong parent (e.g. image under build: instead of under the service) is "additional" where it sits, even though it is valid elsewhere.

A key from a different Compose spec version

A property only valid in another schema version, or removed/renamed, fails validation against the version in use.

How to fix it

Fix the key name and indentation

Correct the typo or move the key to the right level.

docker-compose.yml

services:
  web:
    build: ./web        # not "buld"
    environment:        # not "enviroment"
      - NODE_ENV=production

Validate against the schema

Render the resolved config so the exact offending key is reported.

Terminal

docker compose config

How to prevent it

Run docker compose config in CI before bringing services up.
Use an editor with the Compose JSON schema for inline key validation.
Keep indentation consistent so keys attach to the intended parent.