ERROR: no PostgreSQL user name specified in startup packet
<p>I'm rocking a Phoenix app, and when I try to run <code>mix ecto.migrate</code>, I encounter the following error:</p>

<pre><code>GenServer #PID&lt;0.181.0&gt; terminating
** (Postgrex.Error) FATAL (invalid_authorization_specification): no PostgreSQL user name specified in startup packet
    (db_connection) lib/db_connection/connection.ex:148: DBConnection.Connection.connect/2
    (connection) lib/connection.ex:622: Connection.enter_connect/5
    (stdlib) proc_lib.erl:240: :proc_lib.init_p_do_apply/3
Last message: nil
State: Postgrex.Protocol
</code></pre>

<p>There's some Q&amp;A out there that touches on this particular error, but I haven't found them to be useful, unfortunately. So I turn here!</p>

<p>Additional environment info: Mac OS X, Postgres.app, PG version 9.5</p>