Following directions from here: https://docs.microsoft.com/en-us/azure/active-directory-b2c/user-flow-custom-attributes?pivots=b2c-user-flow
I am able to create and get users fine:
// This works!
var graphServiceClient = new GraphServiceClient(
$"https://graph.microsoft.com/beta",
AuthenticationProvider);
var user = await graphClient.Users[userId].Request().GetAsync();
if (user.AdditionalData == null)
user.AdditionalData = new Dictionary<string, object>();
user.AdditionalData[$"extension_xxxxxxx_Apps] = "TestValue";
// this does not work!
result = await graphClient.Users[user.Id].Request().UpdateAsync(msGraphUser);
For xxxxxxx I tried both the Client ID and Object Id from the b2c-extensions-app in my tenant.
Exception: Microsoft.Graph.ServiceException: 'Code: Request_BadRequest Message: The following extension properties are not available: extension_xxxxxxx_Apps.
what am I missing? How can I set a custom attribute from GraphServiceClient?
Thank you

