Phoenix.NotAcceptableError on "application/dns-message"

I’m getting these errors:

Phoenix.NotAcceptableError: no supported media type in accept header. Expected one of ["html"] but got the following formats: * "application/dns-message" with extensions: [] To accept custom formats, register them under the :mime library in your conf

and I can’t figure out how to make them go away.

Is there a way to automatically respond with 406 for any request made to the server that does not fit the html or json that I’m already handling?

I’m also fine with adding support for these dns-message in my router if this is trivial. I don’t understand the purpose of these messages but maybe they are part of some heartbeat monitoring for the server.

That’s already happening in response to the exception.

In that case, how can I avoid this exception? (sometimes it triggers the overload limit set for rollbar)