Microsoft Graph API returns 502 Bad Gateway (UnknownError) when calling List members of a chat
Description: I am encountering a persistent 502 Bad Gateway error with the UnknownError code when attempting to list members of a specific chat via the Microsoft Graph API v1.0. This issue occurs even though the chat ID is valid and the authorization token has the necessary permissions. API Endpoint: GET /v1.0/chats/{chat-id}/members Steps to Reproduce: 1. Obtain a valid access token with Chat.Read or Chat.ReadWrite permissions. 2. Call the endpoint for a meeting chat: https://graph.microsoft.com/v1.0/chats/19:meeting_NmU5Yjk3NTAtYTk2ZS00Yzg0LWEyYmQtZTJhMjI4NmJjZmRh@thread.v2/members 3. The API returns a 502 Bad Gateway response. Debug Information (Request Details): * Date: 2026-02-06 06:17:55 (GMT) * Request ID: be906f9e-2108-4722-91b8-ecee8bfb41f0 * Client Request ID: be906f9e-2108-4722-91b8-ecee8bfb41f0 * DataCenter: Germany West Central * X-ms-ags-diagnostic: {"ServerInfo":{"DataCenter":"Germany West Central","Slice":"E","Ring":"4","ScaleUnit":"001","RoleInstance":"FR2PEPF0000118F"}} Raw Response Body: { "error": { "code": "UnknownError", "message": "Bad Gateway", "innerError": { "date": "2026-02-06T06:17:55", "request-id": "be906f9e-2108-4722-91b8-ecee8bfb41f0", "client-request-id": "be906f9e-2108-4722-91b8-ecee8bfb41f0" } } } Additional Context: The connection is established successfully via TLS 1.3, but the upstream server seems to be failing. This happens specifically with meeting-related chat threads. Could you please investigate if there is a service degradation or a specific issue with this chat object in the Germany West Central region?