How to fix Unhandled Exception after adding UserActivityMiddleware 'Cannot resolve scoped service 'Microsoft.AspNetCore.Identity.UserManager`1

Question

I had created UserActivityMiddleware for checking every user isActive or not before making any request and then I introduced in the program.cs after authentication and authorization like this app.UseMiddleware<UserActivityMiddleware>(). Then, when I tring to debug there is an unhandled exception in the app.Run();. I used asp.net core 6.

Answer 1

Hi @zerubabel shimeles

UserManager<ApplicationUser> is (by default) registered as a scoped dependency, whereas your UserActivityMiddleware middleware is constructed at app startup (effectively making it a singleton). This is a fairly standard error saying that you can't take a scoped dependency into a singleton class.

To solve this issue, you can inject the UserManager<ApplicationUser> into your Invoke method:

For example:

    public class MyCustomMiddleware
    {
        private readonly RequestDelegate _next;

        public MyCustomMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        // UserManager is injected into InvokeAsync
        public async Task InvokeAsync(HttpContext httpContext, IMessageWriter svc, UserManager<IdentityUser> userManager)
        {
            svc.Write($"Custom middleware: {DateTime.Now.Ticks.ToString()}");

            if (httpContext.User.Identity.IsAuthenticated)
            {

                var username = httpContext.User.Identity.Name;

                var result = await userManager.FindByNameAsync(username);

                svc.Write($"User ID: {username}; User Email: {result.NormalizedEmail}");

            }


            await _next(httpContext);
        }
    }

The result as below:

---

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Best regards,

Dillion