UnknownError when creating a MicrosoftGraph subscription - microsoft-graph-api

Question

I am working on a project to set up a webhook with Microsft graph. I have everything set up to validate the endpoint I have created as per (https://developer.microsoft.com/en-us/graph/docs/concepts/webhooks), however, I am receiving an "Unknown Error" from Microsoft as follows:
"__SLOG0__", "{
\"error\": {
\"code\": \"UnknownError\",
\"message\": \"\",
\"innerError\": {
\"request-id\": \"d0037849-dc79-4244-bb15-cf72841c6653\",
\"date\": \"2018-10-22T20:00:43\"
}
}
}"
I create the subscription with the following values:
$body_vals = dict[
"changeType" => "created,updated",
"notificationUrl" => $notification_uri,
"resource" => "/me/mailfolders('inbox')/messages",
"expirationDateTime" =>
Office365APIUtils::getISO8601DateStamp($date->getTimestamp()),
"clientState" => "SecretClientState",
]
passed into my POST request to the endpoint. I know this has to do with my specific notification uri (which is a facebook endpoint) because if i switch the endpoint to https://google.com, for example, I get a more helpful response:
"__SLOG0__", "{
\"error\": {
\"code\": \"InvalidRequest\",
\"message\": \"Subscription validation request failed. Must respond with 200 OK to this request.\",
\"innerError\": {
\"request-id\": \"4e2ac4af-4d10-416d-83a1-4eb896a35418\",
\"date\": \"2018-10-22T19:52:46\"
}
}
}"
saying I have to validate at the endpoint. I already registered my app, if there is anyone with the Graph team or that has dealt with this before with any leads on these UnknownErrors? an example request-id is 7da743ce-6ffe-4d80-8611-a5be024c8b21

Answer 1

It looks like your code may not be performing the endpoint validation step. This article contains a complete walk-through of how to create a subscription. Have a look at the "Notification endpoint validation" section; your endpoint must be able to respond with 200 and include the validation token.