Upgrade from 1.9 to 2.4 throws "recursive loop detected" error

Ansible newbie alert !

I am upgrading from 1.9 to 2.4. A play that works fine in the former throws up the error:

recursive loop detected in template string: {{ service_down | default(1) }}"}

The last lines in the following two files are of relevance.

Here is one of the plays that includes “application.yml” and seems to be causing the error:

Not sure, but maybe you run into this problem: https://github.com/ansible/ansible/issues/8603

Use a different variable, or what we do:
group_vars are in capital letter. Vars within playbooks or roles are in lowercases.

Thanks. I renamed the variable.