Auze AD Authentication is not working inside webservice method call

Question

Dear Experts,

I am facing challenge to implement Azure AD authentication in my existing application which is webservice (asmx) method.

I have implemented AAD authentication logic in console application its works fine with out any issue.

But its not working while i connect and getting token id its shows following error messages, could you please help to give your advices. greatly appreciated i have to complete it ASAP.

System.InvalidOperationException: There was an error generating the XML document. ---> System.InvalidOperationException: The type System.Threading.Tasks.Task`1[[System.Threading.Tasks.VoidTaskResult, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]] was not expected. Use the XmlInclude or SoapInclude attribute to specify types that are not known statically.
at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriter1.Write2_Task(String n, String ns, Task o, Boolean isNullable, Boolean needType)
at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriter1.Write3_Task(Object o)
at Microsoft.Xml.Serialization.GeneratedAssembly.TaskSerializer.Serialize(Object objectToSerialize, XmlSerializationWriter writer)
at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id)
--- End of inner exception stack trace ---
at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id)
at System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o, XmlSerializerNamespaces namespaces)
at System.Web.Services.Protocols.XmlReturnWriter.Write(HttpResponse response, Stream outputStream, Object returnValue)
at System.Web.Services.Protocols.HttpServerProtocol.WriteReturns(Object[] returnValues, Stream outputStream)
at System.Web.Services.Protocols.WebServiceHandler.WriteReturns(Object[] returnValues)
at System.Web.Services.Protocols.WebServiceHandler.Invoke()

Code Sample:

Answer 1

@Sathish Bonifash , I believe the AcquireTokenForClient() function fails as it is used to implement Client_Credentials flow, but as discussed here in this thread https://learn.microsoft.com/en-us/answers/questions/86362/create-event-in-outlook-calendar-using-azure-ad-ge.html, you would need to use the Authorization Code Grant flow or OpenIDConnect to get this thing working.

You can refer to the following sample: https://github.com/AzureAdQuickstarts/AppModelv2-WebApp-OpenIDConnect-DotNet

Hope this helps.

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