TeamsTab.ReadWriteSelfForTeam: deleting a tab fails with 400 "appId cannot be null or whitespace"

We have a published Teams app that pins a configurable tab into a team channel via Microsoft Graph and removes it again when the user uninstalls our app from that channel. Creating the tab works. Deleting it always fails with a 400 that looks like an unhandled null-argument exception inside the Graph Teams service rather than a permission problem.

I reported this in October 2025 as https://github.com/MicrosoftDocs/msteams-docs/issues/13432, but that is a documentation repository and the issue has had no response, so I am reposting here, as we can still reproduce the issue.

We're using a delegated token for the operation. The only tab-related scopes are `TeamsTab.Read.All` (read-only) and `TeamsTab.ReadWriteSelfForTeam`. According to the docs (https://learn.microsoft.com/en-us/graph/api/channel-delete-tabs), `TeamsTab.ReadWriteSelfForTeam` is the **least privileged** delegated permission for the delete, so the token should be ok.

What works

Creating the tab, with the same delegated user token:

POST https://graph.microsoft.com/v1.0/teams/«teamId»/channels/«channelId»/tabs
Content-Type: application/json

{
  "displayName": "«AppName»",
  "email address removed for privacy reasons": "https://graph.microsoft.com/v1.0/appCatalogs/teamsApps/«teamsAppId»",
  "configuration": {
    "entityId": "«entityId»",
    "contentUrl": "https://«ourhost»/teams/tabs/channel/«entityId»",
    "websiteUrl": "https://«ourhost»/app/tickets?channel=«entityId»",
    "removeUrl": "https://«ourhost»/teams/remove-tab/«entityId»"
  }
}

→ `201 Created`. The tab appears in the channel and renders correctly.

Listing the tabs afterwards also works and returns our tab together with its `id`:

GET https://graph.microsoft.com/v1.0/teams/«teamId»/channels/«channelId»/tabs?$expand=teamsApp

Works as well and lists our tab. Might be served by the TeamsTab.Read.All permission.

What fails

DELETE https://graph.microsoft.com/v1.0/teams/«teamId»/channels/«channelId»/tabs/«tabId»

→ `400 Bad Request`

{
    "error":{
        "code":"BadRequest",
        "message":"appId cannot be null or whitespace. (Parameter 'appId')",
        "innerError":{
            "date":"2026-07-27T13:45:31",
            "request-id":"f930c847-0b48-4a46-b17e-f0ee10ff8177",
            "client-request-id":"f930c847-0b48-4a46-b17e-f0ee10ff8177"
        }
    }
}

(leaving in the error details, maybe that helps diagnosing the issue)

appID is not even part of the request, it's probably resolved against the TeamsTab.ReadWriteSelfForTeam permission on your side.

Let me know if you need any more details.