# 401 error - authentication failed
source: https://developer.mastercard.com/automatic-billing-updater/documentation/code-samples/httpstatus401-authentication-failed/index.md

```json
{
   "Errors":{
      "Error":[
         {
            "Source":"Security.Credential",
            "ReasonCode":"AUTHENTICATION_FAILED",
            "Description":"Unauthorized Access to Web Service",
            "Recoverable":false,
            "Details":"exceptionMessage"
         }
      ]
   }
}
```