Have you run mix ecto.dump and now rely on a structure.sql file to bootstrap a new DB? When you deploy a release to a production-like environment, you don’t have MIX and you can’t run mix ecto.load. See how we can still bootstrap a clean staging environment or deploy to a fresh prod DB! (Spoiler: We’ll steal code from ecto_sql!)

https://fly.io/phoenix-files/loading-structure-sql-on-prod-without-mix/