validating ...\compose.yaml: services.web.enviroment false schema means Compose found a key it does not know at that path. Here environment was misspelled. Correct the key named in the message and run the command again.

The path after the file name is the whole diagnosis: services.web is where the key sits, and the last part, enviroment, is the key Compose rejected. Compare its spelling with the key you meant, letter by letter.

The error

PS> docker compose config --quiet
validating C:\...\c4\compose.yaml: services.web.enviroment false schema

docker compose up stops with the same line before it creates anything. The file that produced it: 

name: fix8-cli-c4
services:
  web:
    image: alpine
    command: ["sleep", "1"]
    enviroment:
      - GREETING=hello

Why it happens

Compose validates the file against the Compose Specification's JSON schema before it does anything else. A service only allows the keys the schema lists, and anything else fails validation. Compose v5.6.1 reported it as false schema. Many older answers online quote Additional property enviroment is not allowed for the same mistake. The message does not suggest the correct spelling, so it is easy to read past a one-letter typo.

The check runs before any container, network or image work, so nothing is created when it fails: both config and up stopped on the same single line. The file is valid YAML, which is why this is not a parser error with a line and column, but a path into the file's structure.

The fix

name: fix8-cli-c4
services:
  web:
    image: alpine
    command: ["sh", "-c", "echo $$GREETING"]
    environment:
      - GREETING=hello
PS> docker compose -f compose.fixed.yaml config --quiet
PS> docker compose -f compose.fixed.yaml up
web-1  | hello

With the key spelled environment, config --quiet prints nothing and exits with 0, and the container sees the variable. Make docker compose config --quiet the first check after editing a Compose file: it validates without creating anything. The up output above is trimmed to the container's own line; the network and container lines around it are left out.

How it was reproduced

Docker Desktop on Windows 11, engine 29.9.2, Docker Compose v5.6.1, Windows PowerShell 5.1, the cached alpine:latest image. A one-service compose.yaml with enviroment gave the message above on both config and up; the corrected file validated and printed hello. The project name fix8-cli-c4 is the test's own; the long folder path is shortened to C:\...\c4, nothing else changed.

Frequently asked

What does false schema mean in docker compose?
Compose validated the file against its JSON schema and found a key that is not allowed at that path. The last part of the path in the message is the rejected key; in this test it was a misspelled environment.
How do I validate a docker compose file without running it?
Run docker compose config --quiet in the folder of the file. It prints nothing and exits with 0 when the file is valid, and prints the problem otherwise.
Is false schema the same as Additional property is not allowed?
Additional property ... is not allowed is the wording many older answers quote for the same mistake, a misspelled or misplaced key. Compose v5.6.1 printed false schema for it in this test.

More decoded errors in the Fixes category. For a Compose file that fails because a dependency is missing, see depends on undefined service.