I got a HTML with a error message first, but then I tried adding ".json" on the end of the URL and got a JSON with a error message (that the URL is wrong), and

I got a HTML with a error message first, but then I tried adding ".json" on the end of the URL and got a JSON with a error message (that the URL is wrong), and then I removed ".json" from the end of te URL and then I got what seems to be the proper JSON response.