How to share a session values between an ASP.NET and ASP.NET Core application?

Question

I have two projects:

1. ASP.NET webforms (.NET 4.8)
2. ASP.NET Core Web API (.NET 6.0)

There are many session values which are used by the ASP.NET webforms app. Since the ASP.NET Core Web API application would be running side-by-side, I need to access these session values in the .NET Core project, too.

I followed the instruction given in

Session sharing between Asp.Net Webforms and Asp.Net Core

but I got Null values in the .NET Core Web API project every time.

Here is my code snippet for the ASP.NET application

Web.config:

I have installed Microsoft.AspNetCore.SystemWebAdapters and Microsoft.AspNet.SessionState:

Global.asax:

Setting a session value:

Changes made to the ASP.NET Core Web API:

Program.cs:

appsettings.json:

Code to retrieve the session value:

Let me know if I am missing anything here.

Thanks in advance

Answer 1

I am checking the source code here, and this is the video.

Please quick test, first

Please open the Contact.aspx page first, make sure the code Session["Test"] = "Hello World"; was excuted.

My Suggestions

The sample code your provided I found 2 issues, but your asp.net web application could be working well and youe asp.net core web app should get error like below

An unhandled exception occurred while processing the request.
ArgumentException: An item with the same key has already been added. Key: Test
System.Collections.Generic.Dictionary<TKey, TValue>.TryInsert(TKey key, TValue value, InsertionBehavior behavior)

Please change it and check it works or not.

In ASP.NET Global.asax.cs

Change

.AddJsonSessionSerializer(options =>
                {
                    // Serialization/deserialization requires each session key to be registered to a type
                    options.RegisterKey<string>("Test");
                    options.KnownKeys.Add("Test", typeof(string));
                })

to

.AddJsonSessionSerializer(options =>
                {
                    // Serialization/deserialization requires each session key to be registered to a type
                    options.RegisterKey<string>("Test");
                    //options.KnownKeys.Add("Test", typeof(string));
                })

In ASP.NET Core Program.cs

Change

.AddJsonSessionSerializer(options =>
    {
        options.RegisterKey<string>("Test");
        options.KnownKeys.Add("Test", typeof(string));
        
    })

to

.AddJsonSessionSerializer(options =>
    {
        //options.RegisterKey<string>("Test");
        options.KnownKeys.Add("Test", typeof(string));
    })

The package in my project.

Asp.net core

Asp.net

If it still not works, please share a Minimal, Reproducible Example, so that I could help you.