Azure App Service API Apps - Microsoft Rest HttpOperationException

Recently I was playing with API Apps, from the new Azure App Service when I faced the following error:

Microsoft.Rest.HttpOperationException`1 was unhandled
  HResult=-2146233088
  Message=Exception of type 'Microsoft.Rest.HttpOperationException`1[System.Object]' was thrown.
  Source=MyMailSenderClient2
  StackTrace:
       at MyMailSenderClient2.Mail.<PostWithOperationResponseAsync>d__0.MoveNext() in c:\DEV\MyTestApi\MyMailSenderClient2\TestMailApi\Mail.cs:line 129
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult()
       at MyMailSenderClient2.MailExtensions.<PostAsync>d__3.MoveNext() in c:\DEV\MyTestApi\MyMailSenderClient2\TestMailApi\MailExtensions.cs:line 42
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
       at MyMailSenderClient2.MailExtensions.Post(IMail operations, MailModel data) in c:\DEV\MyTestApi\MyMailSenderClient2\TestMailApi\MailExtensions.cs:line 24
       at MyMailSenderClient2.Program.Main(String[] args) in c:\DEV\MyTestApi\MyMailSenderClient2\Program.cs:line 16
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

I struggled a bit until I figured why.

Well, let me explain you how I got there and what I have done to solve it.

I access to the new Portal and I created a new API App, then I've followed the Microsoft tutorial of how to Create an ASP.NET API app in Azure App Service.

Everything was going fine and in a few minutes I published the API. Quick and easy.

Then, I generated my Client SDK and when I tried to invoke it, I got the error.

As you can see, the exception message and the stack trace don't provide much information.

I had to struggle a bit to figure it out.

The reason was really simple, my API service had the Access Level defined as Internal.

After changing it to Public (anonymous) everything works fine.

Why this happened? If you follow the tutorial you will create the API App using Visual Studio and you will see that the Visual Studio has the access level Available to Anyone as default.

When you create the API App using the portal, you will see that the Access Level is defined as Internal by default.

I believe that Microsoft will fix these small problems and make it more clear. Until then, I hope that this helps you.