Getting 500 Internal Server Error using the Graph API for TownHalls

Question

Hi,

i am trying to invite people to a existing townhall event using the graph api.
Permission is set properly, i can successfully modify some parameters of the townhall (date, description, etc). But i can not successfully change the InvitedAttendees.

I am using GraphExplorer and Powershell and both result in a "500 Internal Server Error" when i update the list of attendees.
Here the Powershell Error

Update-MgVirtualEventTownhall : Internal Server Error
Status: 500 (InternalServerError)
ErrorCode: InternalServerError
Date: 2025-02-12T08:15:55
Headers:
Transfer-Encoding             : chunked
Vary                          : Accept-Encoding
Strict-Transport-Security     : max-age=31536000
request-id                    : 1c5f57c3-c889-4aac-b37f-26b62155e7eb
client-request-id             : f672f468-eeaf-4c7a-8063-b6671bb2d32d
x-ms-ags-diagnostic           : {"ServerInfo":{"DataCenter":"Germany West Central","Slice":"E","Ring":"4","ScaleUnit":"001","RoleInstance":"FR2PEPF000009C2"}}
scenario-id                   : 4aab6284-4852-442b-bfbd-4a87263747de
Date                          : Wed, 12 Feb 2025 08:15:54 GMT

I even get this error if i submit an Empty JSON Object as list of Attendees. But here as example an object with one Participant (all IDs are valid in my tenant)

$invitedAttendees = @(
    @{
        "@odata.type" = "#microsoft.graph.communicationsUserIdentity"
        id = "545f8ecd-f442-4d97-a095-317f15f3823d"
        displayName = "Mustermann, Max"
        tenantId = "<the real tenantid>"
    }
)

Any Ideas?

Answer 1

Hi Markus Greiner,

Thanks for reaching out to Microsoft!

I tried to reproduce from my end, and able to update the event and received a success response. 500 Internal server error typically indicates that there was an issue on the server side while processing the request. I recommend you raise a support case with Microsoft Graph, a Support Engineer will be able to look into this issue and assist you better. You can raise support ticket from New support request - Microsoft Entra admin center or https://admin.microsoft.com/#/support/requests. 

Hope this helps.

If the answer is helpful, please click Accept Answer and kindly upvote. If you have any further questions about this answer, please click Comment