System.ArgumentNullException from TokenCacheAccessor.CreateRecord, Xamarin.iOS

Which Version of MSAL are you using ? MSAL 2.1.0-preview

Which platform has the issue? Xamarin iOS

What authentication flow has the issue? Mobile - iOS

Repro

public async Task<AuthenticationResult> AcquireTokenAsync() => await publicClientApplication.AcquireTokenAsync(AuthConfig.Scopes, new UIParent());

Expected behavior An token is retrieved and a user record is created in the token cache.

Actual behavior It looks as though the TokenCacheAccessor is failing to create a record after attempting to acquire a token from Azure B2C. It seems specific to the specific B2C policy we’re using. The same workflow works fine in Android, and if I do not provide an Authority to MSAL in iOS, this exception is not thrown.

It doesn’t seem there’s much I can do, as this exception is thrown from within the depths of MSAL, and there don’t seem to be any APIs exposed to handle caching or user records directly.

This issue occurs on both simulator and device. I’ve tried erasing all content and settings on the simulator, doesn’t help.

The fact that I can log in successfully using iOS with the same code but a different B2C policy is interesting. It looks like there’s a particular configuration within this B2C policy that is causing the Xamarin.iOS MSAL library to throw this exception.

Has anyone else encountered this problem?

Here’s the exception:

System.ArgumentNullException: Value cannot be null. Parameter name: str at Foundation.NSString…ctor (System.String str) [0x00009] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/Foundation/NSString.cs:139 at Foundation.NSData.FromString (System.String s, Foundation.NSStringEncoding encoding) [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/Foundation/NSData.cs:208 at Foundation.NSData.op_Implicit (System.String s) [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/Foundation/NSData.cs:214 at Microsoft.Identity.Core.TokenCacheAccessor.CreateRecord (System.String account, System.String service, System.String generic, System.Int32 type, System.String value) [0x00014] in <2a97cd931f1242d58d9f88cc99534e1d>:0 at Microsoft.Identity.Core.TokenCacheAccessor.Save (System.String account, System.String service, System.String generic, System.Int32 type, System.String value) [0x00000] in <2a97cd931f1242d58d9f88cc99534e1d>:0 at Microsoft.Identity.Core.TokenCacheAccessor.SaveAccount (Microsoft.Identity.Core.Cache.MsalAccountCacheItem item) [0x00046] in <2a97cd931f1242d58d9f88cc99534e1d>:0 at Microsoft.Identity.Core.Telemetry.TelemetryTokenCacheAccessor.SaveAccount (Microsoft.Identity.Core.Cache.MsalAccountCacheItem item, Microsoft.Identity.Core.RequestContext requestContext) [0x0001f] in <2a97cd931f1242d58d9f88cc99534e1d>:0 at Microsoft.Identity.Client.TokenCache.SaveAccessAndRefreshToken (Microsoft.Identity.Client.Internal.Requests.AuthenticationRequestParameters requestParams, Microsoft.Identity.Core.OAuth2.MsalTokenResponse response) [0x00178] in <2a97cd931f1242d58d9f88cc99534e1d>:0 at Microsoft.Identity.Client.Internal.Requests.RequestBase.SaveTokenResponseToCache () [0x001bc] in <2a97cd931f1242d58d9f88cc99534e1d>:0 at Microsoft.Identity.Client.Internal.Requests.RequestBase.PostTokenRequest () [0x00008] in <2a97cd931f1242d58d9f88cc99534e1d>:0 at Microsoft.Identity.Client.Internal.Requests.RequestBase+<RunAsync>d__48.MoveNext () [0x00399] in <2a97cd931f1242d58d9f88cc99534e1d>:0 at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00037] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 at System.Runtime.CompilerServices.ConfiguredTaskAwaitable1+ConfiguredTaskAwaiter[TResult].GetResult () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:535 at Microsoft.Identity.Client.PublicClientApplication+<AcquireTokenForLoginHintCommonAsync>d__22.MoveNext () [0x000fb] in <2a97cd931f1242d58d9f88cc99534e1d>:0 at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00037] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 at System.Runtime.CompilerServices.ConfiguredTaskAwaitable1+ConfiguredTaskAwaiter[TResult].GetResult () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:535 at Microsoft.Identity.Client.PublicClientApplication+<AcquireTokenAsync>d__14.MoveNext () [0x0009b] in <2a97cd931f1242d58d9f88cc99534e1d>:0 at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00037] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 at System.Runtime.CompilerServices.TaskAwaiter`1[TResult].GetResult () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.0.0.15/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:357

[PostImpatica]

@jennyf19 Thank you!

[jennyf19]

@helzgate Here is the release for Msal 2.2.1-preview with the fixes and on nuget

If this release does not address your issue, we can reopen this one or start a new one.