C# LINQ: Sequence Contains No Elements Error (but I want to check for null!)

Answer 1

Use FirstOrDefault instead of First. This will return null in the face of an empty collection.

IRepository<User> = new UserRepository();
User user = userRepository.FirstOrDefault(u => u.Name == userName);

Answer 2

Try changing .First() to .FirstOrDefault().

Answer 3

Use .FirstOrDefault() to prevent that error

Answer 4

There are many different way to implement this. you could try:

IRepository<User> = new UserRepository();
User user = userRepository.Where(u => u.Name == userName).Take(1).DefaultIfEmpty;