mailchimp webhook debug error

I get this message in debug when I go to admin web hook page. not sure if it is helpful or a bug

Array
(
    [headers] => Array
        (
            [url] => https://us8.api.mailchimp.com/3.0/lists/d4dcaa5a30/webhooks
            [content_type] => application/problem+json; charset=utf-8
            [http_code] => 400
            [header_size] => 416
            [request_size] => 623
            [filetime] => -1
            [ssl_verify_result] => 0
            [redirect_count] => 0
            [total_time] => 0.23991
            [namelookup_time] => 4.1E-5
            [connect_time] => 0.017989
            [pretransfer_time] => 0.084635
            [size_upload] => 289
            [size_download] => 236
            [speed_download] => 983
            [speed_upload] => 1204
            [download_content_length] => 236
            [upload_content_length] => 289
            [starttransfer_time] => 0.239857
            [redirect_time] => 0
            [redirect_url] => 
            [primary_ip] => 23.64.166.190
            [certinfo] => Array
                (
                )

            [primary_port] => 443
            [local_ip] => 192.168.1.223
            [local_port] => 51556
            [request_header] => POST /3.0/lists/d4dcaa5a30/webhooks HTTP/1.0
User-Agent: DrewM/MailChimp-API/3.0 (github.com/drewm/mailchimp-api)
Host: us8.api.mailchimp.com
Accept-Encoding: deflate, gzip
Accept: application/vnd.api+json
Content-Type: application/vnd.api+json
Authorization: apikey f82b39f30f1f385f06b901df66d55f7e-us8
Content-Length: 289


        )

    [body] => {"type":"https://developer.mailchimp.com/documentation/mailchimp/guides/error-glossary/","title":"Invalid Resource","status":400,"detail":"The resource submitted could not be validated. For field-specific details, see the 'errors' array.","instance":"","errors":[{"field":"url","message":"Invalid URL"}]}
)