LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression.

 public Task<EditUserViewModel> GetUserByRoles(int id)
        {
            return _users.AsNoTracking()
                    .Include(a => a.Roles)
                    .Project(_mappingEngine)
                    .To<EditUserViewModel>()
                    .FirstOrDefaultAsync(a => a.Id == id);
           
               
        }