Authorize attribute does not work with roles

Question

I have a controller level authorize attribute set up like this

[Authorize(Roles = "Administrator")]

And I am adding claims to my user with an overriden UserClaimsPrincipalFactory class that is generates claims like this:

protected override async Task<ClaimsIdentity> GenerateClaimsAsync(ApplicationUser user)
{
    var role = await UserManager.GetRolesAsync(user);
            
    var identity = await base.GenerateClaimsAsync(user);

    identity.AddClaim(new Claim(Options.ClaimsIdentity.RoleClaimType, role.FirstOrDefault()));
            
    return identity;
}

But the due to the authorize attribute, my request that use it, are returning 403, even when the user has the Administrator role.

I have seen numerous problems like this on stackoverflow and on the web, but none of the solutions worked for me.

I have checked multiple times, that I use the correct user, with the correct roles assigned.

EDIT: Added relevant parts from the ConfigureServices method:

services.AddDefaultIdentity<ApplicationUser>(options => options.SignIn.RequireConfirmedAccount = true)
    .AddRoles<IdentityRole>()
    .AddEntityFrameworkStores<ApplicationDbContext>()
    .AddClaimsPrincipalFactory<MyUserClaimsPrincipalFactory>();

services.AddIdentityServer()
    .AddApiAuthorization<ApplicationUser, ApplicationDbContext>();

services.AddAuthentication()
    .AddIdentityServerJwt();

And relevant code from Configure method from Startup.cs:

app.UseAuthentication();
app.UseIdentityServer();
app.UseAuthorization();

I also tried to use policy based authorization with this code and related decorators, but that did not help either:

services.AddAuthorization(options =>
{
    options.AddPolicy("AdministratorOnly", policy => policy.RequireClaim(ClaimTypes.Role,"Administrator"));
});

Answer 1

Try to set a break point to check the "role.FirstOrDefault()" value, whether it is "Administrator" or not (note the spelling).

Besides, try to use identity.AddClaim(new Claim(ClaimTypes.Role, "Administrator"));,

you can refer this screenshot and set the break point in your sample to check the claims: