[Bug] Object Null Reference in GetAuthenticationResultForAppAsync - background task

[xubinzheng]

Which version of Microsoft Identity Web are you using?
Note that to get help, you need to run the latest version.
Microsoft Identity Web 1.23.0

Where is the issue?

• Web app
  • Sign-in users
  • Sign-in users and call web APIs
• Web API
  • Protected web APIs (validating tokens)
  • Protected web APIs (validating scopes)
  • Protected web APIs call downstream web APIs
• Token cache serialization
  • In-memory caches
  • Session caches
  • Distributed caches
• Other (please describe)

Is this a new or an existing app?
c. This is a new app or an experiment.

Repro
We are trying to get an App-only token for MSGraph in C# background task by uisng services.AddHostedService<>();
The code we use to get token:
await _tokenAcquisition.GetAuthenticationResultForAppAsync($"{ResourceId}/.default", tenant: tenantId, null);
Then we received a null Ref error from IdWeb library

Expected behavior
The background task should be able to get an app-only token

Actual behavior
An exception was thrown by IdWeb.

Possible solution

Additional context / logs / screenshots / link to code

Exception details:
at Microsoft.Identity.Web.MergedOptions.PrepareAuthorityInstanceForMsal()
at Microsoft.Identity.Web.TokenAcquisition.BuildConfidentialClientApplication(MergedOptions mergedOptions)
at Microsoft.Identity.Web.TokenAcquisition.GetOrBuildConfidentialClientApplication(MergedOptions mergedOptions)
at Microsoft.Identity.Web.TokenAcquisition.GetAuthenticationResultForAppAsync(String scope, String authenticationScheme, String tenant, TokenAcquisitionOptions tokenAcquisitionOptions)
at Microsoft.Identity.Web.TokenAcquisition.d__19.MoveNext()
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
at Clients.BaseAuthenticationHandler.d__16.MoveNext() in D:\Code\AD-IAM-Services-MyApps\src\Clients\BaseAuthenticationHandler.cs:line 167

[xubinzheng]

Looks like this issue has been fixed in IdWeb 1.23.1 with this PR: #1648

[jennyf19]

released in 1.23.1