How to debug “the given key was not present in the dictionary” when authenticating through webview with Azure and Xamarin

1
votes

I am trying to get server managed authentication working with Visual Studio Mobile Center. It uses Azure App Service Authentication. I was able to setup my Facebook Developer account to allow login, then configured it on Mobile Center, and when I go to the mobile center link for auth in a web browser, it works great.

I setup the client side of the authentication identically to Adrian Hall's examples in his book: https://adrianhall.github.io/develop-mobile-apps-with-csharp-and-azure/chapter2/social/#adding-authentication-to-a-mobile-client

When the webview pops up for facebook, it lets me enter credentials, but then crashes when I hit the submit button. This is the stack trace from the application output window:

System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
[AndroidRuntime]   at System.ThrowHelper.ThrowKeyNotFoundException () [0x00000] in <8c304e4006094a46a7950338a3b3cb5d>:0 
[AndroidRuntime]   at System.Collections.Generic.Dictionary`2[TKey,TValue].get_Item (TKey key) [0x00021] in <8c304e4006094a46a7950338a3b3cb5d>:0 
[AndroidRuntime]   at Microsoft.WindowsAzure.MobileServices.MobileServiceUIAuthentication+<>c__DisplayClass2_0.<LoginAsyncOverride>b__1 (System.Object sender, Xamarin.Auth._MobileServices.AuthenticatorCompletedEventArgs e) [0x00030] in <fe9883f628724025a38f5e1946e5b4c5>:0 
[AndroidRuntime]   at (wrapper delegate-invoke) System.EventHandler`1[Xamarin.Auth._MobileServices.AuthenticatorCompletedEventArgs]:invoke_void_object_TEventArgs (object,Xamarin.Auth._MobileServices.AuthenticatorCompletedEventArgs)
[AndroidRuntime]   at Xamarin.Auth._MobileServices.Authenticator+<>c__DisplayClass22_0.<OnSucceeded>b__0 () [0x00021] in <fe9883f628724025a38f5e1946e5b4c5>:0 
[AndroidRuntime]   at Java.Lang.Thread+RunnableImplementor.Run () [0x0000b] in <a4e9508b230b49a18f145a67e12eb7b8>:0 
[AndroidRuntime]   at Java.Lang.IRunnableInvoker.n_Run (System.IntPtr jnienv, System.IntPtr native__this) [0x00009] in <a4e9508b230b49a18f145a67e12eb7b8>:0 
[AndroidRuntime]   at (wrapper dynamic-method) System.Object:23f66101-d05c-44cc-a8fe-d50bbc9e59d1 (intptr,intptr)

Tested on latest Xamarin Studio and Visual Studio 2017, using Xamarin.Forms 2.3.3, latest Xamarin.Auth, and latest Azure MobileServicesClient.

Any suggestions on how to debug this? I have break on all exceptions checked and I get an Unhandled Exception with a message of "The given key was not present in the dictionary.", no inner exception or stack trace, then it crashes.

EDIT: Reproduction: https://github.com/brandonrisell/TapFriends

1
facebookxamarin.androidazure-mobile-servicesmobile-centervisual-studio-app-center
Do you mean you could browser at https://yoursite.azurewebsites.net/.auth/login/facebook and get the successful authentication page? I followed your sample project, but found the android project could not be compiled successfully, then I added my UWPLoginProvider and point the MobileServiceClient to my mobile app, it could work (list items, add new item,etc.). Firstly, please try to check await mobileCenter.LoginAsync() of your LoginViewModel within the shared project and find whether you could get the logged info, then step by step to debug your code and try to find the cause. – Bruce Chen
The key-not-found is likely to be the response from the service. Can you possibly turn on diagnostic logging at the verbose level in your service and watch the log stream for the auth event. Add any logs that you receive (appropriately edited for private information) so we can see those? – Adrian Hall

1 Answers

2
votes
  1. Open the Azure Portal
  2. Find the resource group for your Mobile Center backend
  3. Open up the Mobile Apps resource
  4. Select Authentication / Authorization
  5. Check that the Token store is turned on.

If it isn't, turn it on, save then restart and recheck.

I think that's the problem. If not, get back to me here and we'll try something else.