How to call Microsoft Graph Beta API from C#

The api-version query parameter is used by the Azure AD Graph API. This is a different API than Microsoft Graph. There is a lot of functional overlap (Azure AD Graph is slowly being migrated over to Microsoft Graph) but they use entirely different entities and calling conventions.

In order to call the /beta endpoint using the Microsoft Graph .NET Client Library, you need to change the BaseUrl of the client:

graphClient.BaseUrl = "https://graph.microsoft.com/beta";
var pictureStream = await graphClient.Me.Photo.Content.Request().GetAsync();

Some important notes about the /beta endpoint:

1. It isn't supported and isn't suitable for production. So don't do that. Or at least don't tell anyone and don't call Support if it stops working. ;-)

2. The .NET Client uses objects constructed off the production metadata. This means that any entities, actions or properties that were added in /beta don't exist in the models shipped with the SDK.

3. The .NET Client will ignore any values returned by Microsoft Graph that it doesn't expect to see. So if an endpoint returns a property that wasn't included in the production metadata (see #2), it will simply be ignored.

   So long as you're only using a /beta to gain functionality but still expecting /v1.0 results, it should work okay. Photos for example only look at Exchange in v1.0 but look in both Exchange and Active Directory but still return the same result. In theory this means you should be able to swap /beta for /v1.0 without a problem.