ASP.NET Core doesn't create an authentication cookie when SameSite is set to none

Question

I want to test a cross-domain authentication after some research it seems SameSite for authentication cookie should be set to none as below:

options.Cookie.SameSite = SameSiteMode.None;

The problem is that when I set SameSite to none, the application can not create an authentication cookie but if set it to Lax or strict it works fine.

This is my code in program.cs:

builder.Services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
.AddCookie(options =>
           {
               options.Cookie.Name = "authen";
               options.Cookie.HttpOnly = true;
               options.Cookie.SecurePolicy = CookieSecurePolicy.None;
               options.Cookie.SameSite = SameSiteMode.None;
               options.Cookie.Path = "/";
               options.Cookie.Domain = "localhost";
           });

Update

After some testing, it seems this happens only in Google Chrome and it works on Firefox fine.

Answer 1

Change this line code to

options.Cookie.SecurePolicy = CookieSecurePolicy.None;

to

options.Cookie.SecurePolicy = CookieSecurePolicy.Always;

and it works.