Subscription validation request failed. Response must exactly match validationToken query parameter

Question

The Microsoft webhook subscription is sending weird body data and no text in the validationToken parameter. Is there anyone on the Microsoft Graph team that could help?

This is what I'm sending (I changed the actual domain name in the notificationUrl for privacy).

{
    "changeType": "created",
    "notificationUrl": "https://myapp.com/version-test/api/1.1/wf/msgraphvalidation",
    "resource": "me/mailFolders/inbox/messages",
    "expirationDateTime": "2018-08-27T18:23:45.9356913Z"
 }

This is what's being returned in the body after sending a POST to "https://graph.microsoft.com/v1.0/subscriptions" or "https://graph.microsoft.com/beta/subscriptions" with the above info.

Request data
{
    "bold": "\u001b[1m\u001b[22m",
    "underline": "\u001b[4m\u001b[24m",
    "strikethrough": "\u001b[9m\u001b[29m",
    "italic": "\u001b[3m\u001b[23m",
    "inverse": "\u001b[7m\u001b[27m",
    "grey": "\u001b[90m\u001b[39m",
    "black": "\u001b[30m\u001b[39m",
    "yellow": "\u001b[33m\u001b[39m",
    "red": "\u001b[31m\u001b[39m",
    "green": "\u001b[32m\u001b[39m",
    "blue": "\u001b[34m\u001b[39m",
    "white": "\u001b[37m\u001b[39m",
    "cyan": "\u001b[36m\u001b[39m",
    "magenta": "\u001b[35m\u001b[39m",
    "greyBG": "\u001b[49;5;8m\u001b[49m",
    "blackBG": "\u001b[40m\u001b[49m",
    "yellowBG": "\u001b[43m\u001b[49m",
    "redBG": "\u001b[41m\u001b[49m",
    "greenBG": "\u001b[42m\u001b[49m",
    "blueBG": "\u001b[44m\u001b[49m",
    "whiteBG": "\u001b[47m\u001b[49m",
    "cyanBG": "\u001b[46m\u001b[49m",
    "magentaBG": "\u001b[45m\u001b[49m",
    "rainbow": "",
    "zebra": "",
    "stripColors": "",
    "zalgo": ""
}

Here's the full error:

{ 
"error": { 
    "code": "InvalidRequest", 
    "message": "Subscription validation request failed. Response must exactly match validationToken query parameter.",
    "innerError": { 
        "request-id": "08008b1b-4eda-4a09-a0d5-45ffcce1a8d6", 
        "date": "2018-08-26T02:43:08" 
    }
}
}

Answer 1

Microsoft Graph validates the notification endpoint provided in the notificationUrl property of the subscription request before creating the subscription. Refer to the following links:

https://developer.microsoft.com/en-us/graph/docs/concepts/webhooks

Microsoft Graph WebHook: Subscription validationtoken blank?

You can validate the notification url like this:

if (Request.QueryString["validationToken"] != null)
            {
                var token = Request.QueryString["validationToken"];
                return Content(token, "text/plain");
            }

https://github.com/microsoftgraph/aspnet-webhooks-rest-sample/blob/master/GraphWebhooks/Controllers/NotificationController.cs