B2C Authentication with WebForms - webforms

Question

I have a legacy WebForms application. I need to add Azure B2C authentication to it. My application is using currently Microsoft.Aspnet.Identity. It does not have any startup.cs page. How can I make this migration?

Answer 1

Some minor things allow you to switch your site to use AAD or aadb2c for authentication.
Get the necessary OWIN NuGet packages, Add some startup code to use the OWIN authentication libraries ,Register your application in AADb2c.
Update your web.config with appropriate OAuth values.
Even though OWIN didn’t exist when you wrote your Web Forms app, you can still use it and it will significantly simplify the process.
In the Visual Studio menu, select Tools > NuGet Package Manager > Package Manager Console.
Make sure your web project is selected in the Default project drop down.
Run the below commands:
install-package Microsoft.Owin.Host.SystemWeb
install-package Microsoft.Owin.Security.OpenIdConnect
install-package Microsoft.Owin.Security.Cookies
You may check the references and then follow this B2C-WebForms-DotNet
References:
c# - ASP.NET Web Api - Startup.cs doesn't exist - Stack
Overflow
c# - OWIN Startup Class Missing - Stack Overflow
edit:
My web forms if for visual C# and could find owin start up :
Right click on App_Start > add item > under web , you can find it.
Please check if your project is visual c# .
edit 2:
Please check if below points help :
Maybe you can create new start up class by using owin library in the clas
Imports Microsoft.Owin.Extensions
Imports Microsoft.Owin.Security
Imports Microsoft.Owin.Security.Cookies
Imports Microsoft.Owin.Security.OpenIdConnect
Imports Owin
Imports System
Imports System.Configuration
Check the web.config file and remove this key setting and try
<add key="owin:AutomaticAppStartup" value="false" />
and also try add <add key="owin:AutomaticAppStartup" value="true " /> in web.config file
The following attribute will set the startup class to the StartUp class in the StartupDemo namespace.
[assembly: OwinStartup(typeof(StartupDemo.StartUp))]
Add appSetting element in the Configuration file
<appSettings>
<add key="owin:appStartup" value="StartupDemo.StartUp" />
</appSettings>
Check how owin detects start up owin-startup-class-detection -Microsoft docs
Other references:
owin-startup-class-not-detected
owin-with-vb-net-legacy-code-asp-net-web-forms
where-to-implement-startup-code-in-vb-net