You are missing DATABASE_URL from your environment. You can see that this guy db.default.url=${?DATABASE_URL} is trying to use it.

So before starting "activator run" or running "heroku local web -f" (or something else you start the local server with), you need to "set" a link to the Postgres you want to use.

This works for quick local hack (first install Postgres locally, it asks you to set the postgres user's password):

set DATABASE_URL=postgres://postgres:<PASSWORD>@localhost:5432/<DB_NAME>

, where is the one you set when installing, and the name of the database inside Postgres you want to be used (create one there using psql).

After this the server runs.

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