Error installing `rebar`(Failed updating session)

[jessykate]

When running mix ecto.create && mix ecto.migrate the process gets down to ==> drft and then I get an error Could not find "rebar", which is needed to build dependency :ranch.

Answering yes to installing rebar gives an error: Failed updating session.

[jessykate]

The process keeps going, then at the end says

The database for Drft.Repo has been created
** (Mix) Could not find migrations directory "priv/repo/migrations" for repo Drft.Repo