Azure Active Directory - UI > API - 401 Error - azure-active-directory

Question

Good Day,
Currently I have a single tenent with a React UI and .NET Core Apis secured by Azure Active Directory without any problems.
We have recently moved to a new Azure Tenent, new Active Directory etc. I have create two new App Registrations, one single App Service for UI and one for API. I have linked the App Service to AAD (UI = UI App Registration, API = API App Registration).
The problem is the API is getting a 401 error and I think see that in the original tenent the Bearer token is in a JWT format but in the new instance it's not, I believe it my be a graph api access key.
New Tenent:
Authorization: Bearer PAQABAAAAAAD--DLA3VO7QrddgJg7WevrQvEQVbZEMD8su-tIp9k2bTFUTort7SZgeDI52P6KRYefHgtmj4YrecgUKZJ2wylGuhvIzIz642n7Sg0VMU1RwKtrzWlaMqK62CaSoJcstxiEf6 *****
Orginal Tenent:
Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsIng1dCI6Im5PbzNaRHJPRFhFSzFqS1doWHNsSFJfS1hFZyIsImtpZCI6Im5PbzNaRHJPRFhFSzFqS1doWHNsSFJfS1hFZyJ9.eyJhdWQiOiI3OThkN2ZkOC0zODk2LTQxOGMtOTQ0Ny0wNGFlNTQ2OGFkNDIiLCJpc3MiOiJodHRwczovL3N0cy53aW5kb3dzLm5ldC83ZDE3NTU3Ni03Y2Y3LTQyMDctOTA5My0wNmNiNmQyZDIwNjAvIiwiaWF0IjoxNjE2NDUyNzExLCJuYmYiOjE2MTY0NTI3MTEsImV4cCI6MTYxNjQ1NjYxMSwiYWNyIjoiMSIsImFpbyI6IkFTUUEyLzhUQUFBQU9mejhPZHp *****
Please someone kindly enought to provide some guidance / input where I am going wrong.
Regards
Paul.

Answer 1

When using Azure AD to obtain an access token, an additional resource parameter is required. Otherwise, the access token is not a JWT.
For example, if your web API's application ID URI is https://contoso.com/api and the scope name is Employees.Read.All, then with oidc-client the client configuration should be :
scope: 'openid profile email Employees.Read.All',
extraQueryParams: {
resource: 'https://contoso.com/api'
}
In App Service auth configuration, you can use additionalLoginParams
"additionalLoginParams": ["response_type=code", "resource=https://contoso.com/api"]
If you did not use a custom application ID URI, it may look like
api://868662dd-3e28-4c7f-b7d5-7ec02ac9c601
Quickstart: Configure an application to expose a web API

Answer 2

Firstly, the scope is incorrect.
You should Expose an API in your API App Registration and then add it as a permission in your UI App Registration. You can refer to this document.
And when you try to call the 'https://login.windows.net/{tenant}/oauth2/authorize endpoint, you need to specify the scope to include api://{app id of the API App Registration}. For example: api://{app id of the API App Registration} openid profile email. Then the access token would be for calling your API.
At last, for CORS issue, please configure the CORS as * in your web app to see if it helps.

Answer 3

Try to follow this step: Configure App Service to return a usable access token

Answer 4

In my experience, this problem occurs, when you try to authorize against version 1 of the endpoint.
Instead of calling
https://login.microsoftonline.com/{tenant}/oauth2/authorize
call
https://login.microsoftonline.com/{tenant}/oauth2/v2.0/authorize
You might be required to set something like "metadata URL" in you authorization library to:
https://login.microsoftonline.com/{tenant}/oauth2/v2.0/.well-known/openid-configuration

Answer 5

Make sure your builder follows this order...lifted from our API program.cs
These must be in order of
UseRouting -> UseAuthentication -> UseAuthorisation -> MapControllers
> app.UseRouting()
> app.UseAuthentication()
> app.UseAuthorization()
> app.MapControllers()
If app.UseAuthentication and app.UseAuthorization are not in this order in statement position you Will get 401 Unauthorised as at 01/2023 .Net 6 Core.