[Bug] Throw a better exception when ROPC is attempted with MSA account

Which Version of MSAL are you using ? 4.22

Attempt ROPC, with authority correctly set to l.m.o/organizations. Provide an MSA username to the API.

Expected an exception explaining the root cause.

Implementation suggestion:

• We could use either the “domain_name” from the userrealm call (need to confirm with MSA folks)

• Or the fact that the subsequent call to GET /FederationMetadata/2007-06/FederationMetadata.xml HTTP/1.1 fails with 406 Not Acceptable.

Actual a bad exception which causes developers to think there is a bug in MSAL

—> System.InvalidOperationException: Sequence contains no elements at System.Linq.ThrowHelper.ThrowNoElementsException() at System.Linq.Enumerable.First[TSource](IEnumerable1 source) at Microsoft.Identity.Client.WsTrust.MexDocument.SetPolicyEndpointAddresses(XContainer mexDocument) at Microsoft.Identity.Client.WsTrust.MexDocument..ctor(String responseBody) at Microsoft.Identity.Client.WsTrust.WsTrustWebRequestManager.GetMexDocumentAsync(String federationMetadataUrl, RequestContext requestContext) at Microsoft.Identity.Client.WsTrust.CommonNonInteractiveHandler.PerformWsTrustMexExchangeAsync(String federationMetadataUrl, String cloudAudienceUrn, UserAuthType userAuthType, String username, SecureString password) at Microsoft.Identity.Client.Internal.Requests.UsernamePasswordRequest.FetchAssertionFromWsTrustAsync() at Microsoft.Identity.Client.Internal.Requests.UsernamePasswordRequest.ExecuteAsync(CancellationToken cancellationToken) at Microsoft.Identity.Client.Internal.Requests.RequestBase.RunAsync(CancellationToken cancellationToken) at Microsoft.Identity.Client.ApiConfig.Executors.PublicClientExecutor.ExecuteAsync(AcquireTokenCommonParameters commonParameters, AcquireTokenByUsernamePasswordParameters usernamePasswordParameters, CancellationToken cancellationToken) at Azure.Identity.AbstractAcquireTokenParameterBuilderExtensions.ExecuteAsync[T](AbstractAcquireTokenParameterBuilder1 builder, Boolean async, CancellationToken cancellationToken) at Azure.Identity.MsalPublicClient.AcquireTokenByUsernamePasswordAsync(String[] scopes, String username, SecureString password, Boolean async, CancellationToken cancellationToken) at Azure.Identity.UsernamePasswordCredential.GetTokenImplAsync(Boolean async, TokenRequestContext requestContext, CancellationToken cancellationToken) — End of inner exception stack trace —

[bgavrilMS]

Yeah, I think approach 1 is cleaner.

[jennyf19]

@rayluo that’s interesting because we do get the 406 error. We went w/option 1 based on conversation w/ests. will loop you in on the email.