max.Verbose = true
form := url.Values{}
// ... populate form
targetURL := fmt.Sprintf("ssl.json/%s", certID)
var put maxcdn.Generic
res, err := max.Put(&put, targetURL, form)

Response: HTTP/2.0 500 Internal Server Error                                                                                                                                                                       
Access-Control-Allow-Origin: *                                                                                                                                                                                     
Cache-Control: max-age=3600, must-revalidate                                                                                                                                                                       
Content-Type: application/json                                                                                                                                                                                     
Date: Thu, 03 Sep 2020 13:46:51 GMT                                                                                                                                                                                
Etag: 89335e0158b9691b9d4a61c4ec6309cf                                                                                                                                                                             
Server: nginx                                                                                                                                                                                                      
Vary: Accept-Encoding                                                                                                                                                                                              
X-Xrds-Location: http://rws.maxcdn.com/services.xrds                                                                                                                                                               
                                                                                                                                                                                                                   
{"code":500,"error":{"message":"Invalid signature","type":""}}