ERROR: In file './docker-compose.yml', volume must be a mapping not a string

Question

Question: Why do I get this error?

ERROR: In file \'./docker-compose.yml\', volume \'mariavolume\' must be a mapping not a string.

Answer 1

I was running into the same issue as yourself and as a last act of despair I tried putting

volumes:
  - maria_volume: /var/lib/mysql

before

environment:
  MYSQL_ROOT_PASSWORD: example

I'm not sure what kind of magic applied here but in my case, it worked

Let me know!