Q:

Failed to get open extension when use delta

I am using Microsoft Graph. First I added open extension to mail by
POST /me/messages/{messageId}/extensions

{
  "@odata.type": "Microsoft.Graph.OpenTypeExtension",
  "extensionName": "myExtension",
  "virtualId": "12345"
}

Then I can successfully get those mails with extensions by
GET /me/mailfolders/SentItems/messages?$expand=extensions($filter=id eq 'myExtension')

But I failed to get when I use delta by
GET /me/mailfolders/SentItems/messages/delta?$expand=extensions($filter=id eq 'myExtension')

It gives me error:

{
    "error": {
        "code": "InternalServerError",
        "message": "Value cannot be null.\r\nParameter name: type",
        "innerError": {
            "request-id": "89f54294-b49b-410b-99d0-0c2df9d90f1d",
            "date": "2017-11-20T04:50:57"
        }
    }
}

How to get open extension when use delta?

A:

Already answered this via email, but posting here as well to close the loop. We do not support delta query on open extension properties today. This is something we want to support in the future, but we don't have specific plans yet.

