MVC Email Confirmation (Sequence contains more than one element) - asp.net-mvc

Question

I'm currently trying to add email confirmation to my website and i'm experiencing a few problems.
I can succesfully register an account, upon registration the confirmationToken gets placed in my database and a email gets send with the query string link: http://www.example.com/RegistrationConfirmation?9ZPwZZrO-UmdpVpxXWjmRw when going to this link the controller action RegistrationConfirmation gets called and the method ConfirmAccount does a query to see if we can find a user with the confirmation token that was passed in the url.
When debugging I get the error "Sequence contains more than one element" on this line: Account user = context.Accounts.SingleOrDefault(u => u.ConfirmationToken == confirmationToken);
I'm not sure what's going wrong cause the token is unique and there are no duplicate tokens in the database.
Register HttpPost:
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Register(RegisterModel model)
{
string confirmationToken = CreateToken();
Account account = new Account(model.Username, model.Password, model.FirstName, model.LastName, model.Email, false, confirmationToken);
if (DatabaseHandler.isUsernameDuplicate(account.Username))
{
// is duplicate // provide notification
}
else
{
Session["accountID"] = Repository.InsertAccount(new Account(model.Username, model.Password, model.FirstName, model.LastName, model.Email,false, confirmationToken));
// Email Logic
try
{
await client.SendMailAsync(message);
}
catch (Exception e)
{
ModelState.AddModelError("", "Problem sending email: " + e.Message);
}
return View("ConfirmEmail");
}
return View();
}
RegistrationConfirmation HttpGet:
[HttpGet]
[AllowAnonymous]
public ActionResult RegisterConfirmation(string Id)
{
if (ConfirmAccount(Id))
{
return RedirectToAction("ConfirmationSuccess");
}
return RedirectToAction("ConfirmationFailure");
}
ConfirmAccount method:
private bool ConfirmAccount(string confirmationToken)
{
RecipeDbContext context = new RecipeDbContext();
Account user = context.Accounts.SingleOrDefault(u => u.ConfirmationToken == confirmationToken);
if (user != null)
{
user.IsConfirmed = true;
DbSet<Account> dbSet = context.Set<Account>();
dbSet.Attach(user);
context.Entry(user).State = EntityState.Modified;
context.SaveChanges();
return true;
}
return false;
}

Answer 1

Remove SingleorDefault() and check the result.. you will get to know its not duplicate and if you want to avoid this error then use FirstorDefault().

Answer 2

Turned out nothing was wrong with the query itself, the RegisterConfirmation HttpGet did not seem to get the confirmToken value so I added "Id = Request.QueryString.ToString();" and everything is working perfect now :)