No function clause matching in SmartcomClientWeb.TemplateController.create/2

Do you really send a map with a key template? Maybe you just send the template_params rawly.
kokolegorille is right, IO.inspect is a good idea here.

But i notice that the inspect won’t never be executed. It will fail immediately for the same reason.
Try this:

def create(conn, params) do
  IO.inspect(params, label: "PARAMS")
end