Microsoft Graph - PopAuthenticatorInvalidSignature errors when patching to calendar events

Question

We're seeing errors with the graph api when making a PATCH request to https://graph.microsoft.com/v1.0/me/calendars/$(CALENDAR_ID)/events/$(EVENT_ID).

This is in an integration that has been in production for some time and we've never seen this before. Is this a bug with the api, downtime, or something we should handle on our end? Here's an example response:

HTTP 401
{
  "error": {
    "code": "PopAuthenticatorInvalidSignature",
    "message": "Signature is invalid for pop authenticator.",
    "innerError": {
      "date": "2019-09-25T18:33:37",
      "request-id": "1383b020-6ba0-44db-85b8-03cfbf277cd3"
    }
  }
}

Here are additional request ids:

0c2a47da-1090-4c06-b5cb-fc95b3964913
7403116f-3edd-4d39-adf9-51ed2feaee23
27df39b8-43ad-41f8-b9f1-b5e2adaafb4b
408c8686-bf78-4a82-883a-7e794838d846
7130b609-1a0a-46f2-b523-0db1db591fe1
9659a797-180f-4f41-bba0-b1b490408752
161ea8d8-dcf5-4f0d-aa21-32b584e22ba6

Happy to provide additional information if needed.

Answer 1

This was a server side issue that's now been rectified.

Answer 2

I've seen this exact issue across multiple customers' Graph applications. It's been sporadic since at least yesterday and as of roughly 17:30 Central today, it's stopped happening completely. It certainly looks like some sporadic API outage/issue.

We have not re-registered any applications - it just stopped failing on its own. We've encountered this issue with apps that have been registered with both the old and the new app registration system, so I don't think it's related at all.

I read the deprecation notice on the old app registration portal as saying that the old portal is deprecated, not that any previously registered apps are deprecated and need to be re-registered. Microsoft would never silently break nearly everyone's API access like that.