AddIdentity() fails “InvalidOperationException: Scheme already exists: Identity.Application”

Question

I\'m trying to add facebook login to my .NET Core 2.1 site

I\'m following this , guide and more specific, this (for facebook login)

After have adding the lines

Answer 1

For me (ASP.NET Core v2), I had:

services.AddIdentity()
                    .AddEntityFrameworkStores()
                    .AddUserStore()
                    .AddRoleStore()
                    .AddRoleManager()
                    .AddDefaultTokenProviders();

in Startup.cs. And when I scaffolded Identity, it added IdentityHostingStartup.cs, and I had copy/pasted another similar but default block in based on some email sending code:

builder.ConfigureServices((context, services) =>
                {
                    services.AddDefaultIdentity(config =>
                    {
                        config.SignIn.RequireConfirmedEmail = false;//TODO:
                    })
                    .AddEntityFrameworkStores();
                });

So I moved ALL Identity config into IdentityHostingStartup.cs (ie only 1 configure!!!) it worked as expected...