Unable to use “OfficeDevPnP.Core.AuthenticationManager().GetAppOnlyAuthenticatedContext” inside ASP.NET core (.NET 5)

Question

I have the following CSOM code inside my ASP.NET CORE (.NET 5.0):-

var siteUrl = config.GetSection("SP").GetSection("SiteURL").Value;             
string clientId = "****";  
string clientSecret = "***";  
  
     using (ClientContext context = new OfficeDevPnP.Core.AuthenticationManager().GetAppOnlyAuthenticatedContext(siteUrl, clientId, clientSecret))  
  
        {  

but i am getting this error:-

System.TypeInitializationException  
  HResult=0x80131534  
  Message=The type initializer for 'OfficeDevPnP.Core.Utilities.TokenHelper' threw an exception.  
  Source=OfficeDevPnP.Core  
  StackTrace:  
   at OfficeDevPnP.Core.Utilities.TokenHelper.set_Realm(String value)  
   at OfficeDevPnP.Core.AuthenticationManager.EnsureToken(String siteUrl, String realm, String appId, String appSecret, String acsHostUrl, String globalEndPointPrefix)  
   at OfficeDevPnP.Core.AuthenticationManager.GetAppOnlyAuthenticatedContext(String siteUrl, String realm, String appId, String appSecret, String acsHostUrl, String globalEndPointPrefix)  
   at OfficeDevPnP.Core.AuthenticationManager.GetAppOnlyAuthenticatedContext(String siteUrl, String appId, String appSecret)  
   at ServiceDeskSharePointIntegration.Program.Main(String[] args) in C:\Users\****\source\repos\ServiceDeskSharePointIntegration\ServiceDeskSharePointIntegration\Program.cs:line 47  
  
Inner Exception 1:  
TypeLoadException: Could not load type 'System.Web.Configuration.WebConfigurationManager' from assembly 'System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.  

when i hover over the related package i got this error:-

Answer 1

SharePointPnPCoreOnline is no longer maintained, please use PnP Framework (https://github.com/pnp/pnpframework) going forward.
And test code for your reference:

ClientContext ctx = new AuthenticationManager().GetACSAppOnlyContext("https://contoso.sharepoint.com/sites/dev", "app id", "app secret", AzureEnvironment.Production);  

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