Is there a way to fix 400 error in ASP.NET Core MVC

Question

I try to generate an Email confirmation token, I successfully generate it and the put it in the link alongside with the user id that I send to the registered user. The email arrives, and when I hover my mouse over it the link shows the "right way". And when I click on it, I get the following error:

I tried a few different way, but I can't make it work. My code is below:

[HttpPost]
        public async Task<IActionResult> SignUp(RegisterViewModel model)
        {
            var user = new ApplicationUser { UserName = model.UserName, Email = model.Email };

            var result = await _userManager.CreateAsync(user, model.Password);

            if (result.Succeeded)
            {
                await _userManager.AddToRoleAsync(user, "User");

                var confirmationToken = await _userManager.GenerateEmailConfirmationTokenAsync(user);

                var confirmationLink = $"https://localhost:44314/Account/VerifyEmail?userId={user.Id}&confirmationToken={confirmationToken}";

                MailMessage mailMessage = new MailMessage
                (
                    new MailAddress(_configuration.GetValue<string>("Smtp:From"),
                    _configuration.GetValue<string>("Smtp:Username")),
                    new MailAddress(model.Email)
                );

                mailMessage.Subject = _configuration.GetValue<string>("Smtp:ConfirmRegister");
                mailMessage.Body = $"<a href=\"{confirmationLink}\">Verify Email</a>";
                mailMessage.IsBodyHtml = true;

                SmtpClient smtp = new SmtpClient();
                smtp.Host = _configuration.GetValue<string>("Smtp:Server");
                smtp.Port = _configuration.GetValue<int>("Smtp:Port");
                smtp.EnableSsl = true;
                smtp.DeliveryMethod = SmtpDeliveryMethod.Network;

                System.Net.NetworkCredential networkCredential = new System.Net.NetworkCredential();
                networkCredential.UserName = _configuration.GetValue<string>("Smtp:From");
                networkCredential.Password = _configuration.GetValue<string>("Smtp:Password");
                smtp.UseDefaultCredentials = false;
                smtp.Credentials = networkCredential;

                smtp.Send(mailMessage);

                return RedirectToAction("Index", "Home");
            }

            foreach (var error in result.Errors)
            {
                _toastNotification.AddErrorToastMessage(error.Description, new ToastrOptions()
                {
                    Title = "Ooops!"
                });
                ModelState.AddModelError(string.Empty, error.Description);
            }

            return View(model);
        }

        public async Task<IActionResult> VerifyEmail(string userId, string confirmationToken)
        {
            var user = await _userManager.FindByIdAsync(userId);

            if (user == null) _toastNotification.AddErrorToastMessage("Error");
                var result = await _userManager.ConfirmEmailAsync(user, confirmationToken);

                if (result.Succeeded)
                {
                    return View();
                }

                return BadRequest();
        }

Answer 1

I found a solution here: Invalid Token. while verifying email verification code using UserManager.ConfirmEmailAsync(user.Id, code)

To make it work, I just had to encode the token:

HttpUtility.UrlEncode(tokenGoesHere);