Just posting this here in case it helps anyone else in future. on mix ecto.create I was getting: 00:54:48.033 [error] GenServer #PID<0.214.0> terminating ** (Postgrex.Error) FATAL 28000 (invalid_authorization_specification) role "postgres" does not exist (db_connection) lib/db_connection/conne…

Fixed with: createdb 'Aston' psql (Change Aston to whatever the psql command in the post above said was missing) Then: CREATE USER postgres SUPERUSER; CREATE DATABASE postgres WITH OWNER postgres; exit (Although it told me the postgres db already exists - something you can check with psql -l) …

Ah that explains why when using Rails it works fine - because I guess they use your account name user rather than ‘postgres’. I wonder if Ecto could detect whether you’re using OSX and do the same? Otherwise every Mac user who have installed PG via homebrew will get the same. Alternatively maybe h…

So for me the disconnect is that the generators hard-code the literal value of “postgres” for username on the Ecto connection, but really what it needs is a SQL user that is a superuser or that has DB creation rights. I would prefer some explicitness/agnosticism in that direction be included in the …

Not sure. I installed PG through homebrew as well and I seem to remember it having the postgres user and a fresh Phoenix app working right away. But then again, that was a while ago, can’t swear the details on my life. As for the Ecto default, you’re not wrong but then again they apply for local-on…

But if you’re working on a shared project, you’re probably better off with everyone using the postgres user locally, or not setting one at all (which I think will default to the logged in user)

Hi guys! I got the same error: 16:05:28.295 [error] GenServer #PID<0.220.0> terminating ** (Postgrex.Error) FATAL 28000 (invalid_authorization_specification) no PostgreSQL user name specified in startup packet (db_connection) lib/db_connection/connection.ex:84: DBConnection.Connection.connect/2…

I’m thinking you need to have a look at your pg_hba.conf and make sure you are actually permitted to log into Postgres. Have you tried getting in simply with psql -U postgres?

From here: https://stackoverflow.com/questions/15301826/psql-fatal-role-postgres-does-not-exist#comment-91332745 /usr/local/opt/postgres/bin/createuser -s postgres Fixed it for me. The problem is homebrew doesn’t install the postgres user.

Got the same issue with PostgreSQL on macOS installed from brew. Resolved with the next config: config :p_core, PCore.Repo, username: System.cmd("whoami", []) |> elem(0) |> String.trim(), database: "p_core_dev", hostname: "localhost", show_sensitive_data_on_connecti…

Thank you, this ended up being my issue!

This ended up being my issue as well on Mac OS - I needed to replace user / password with my local machine credentials.

'mix ecto.create' errors with: role "postgres" does not exist

Questions & Help Questions

leifericf November 2, 2025, 12:16pm 25

Thanks! I did indeed miss that part of the docs. And now it’s sorted!