Failed to load resource: the server responded with a status of 500 (Internal Server Error) code example

Example 1: failed to load resource: the server responded with a status of 404 (not found)

<script  src="../../Jquery/prettify.js"></script>

Example 2: The server responded with error 50007

foreach (var user in users)
            {
                var u = user as IGuildUser;

                if (!u.IsBot && !u.IsWebhook)
                {
                    try
                    {
                        await u.SendMessageAsync("Hi");
                    }
                    catch (Exception e)
                    {
                        var useless = e;
                    }
                }
            }

Example 3: The server responded with error 50007

[Command("dm")]
        public async Task DmAsync()
        {
            var guild = Program._client.GetGuild(Context.Guild.Id) as IGuild;
            await Context.Guild.DownloadUsersAsync();
            await Task.Delay(500);
            var users = await guild.GetUsersAsync();

            foreach (var user in users)
            {
                var u = user as IGuildUser;

                if (!u.IsBot && !u.IsWebhook)
                {
                    IUserMessage dm = await u.SendMessageAsync("Mass dm test", false);

                    if (dm == null)
                    {
                        continue;
                    }
                }
            }
        }

Example 4: failed to load resource the server responded with a status of 400 ()

The answer was the Wrapper class. It couldn't assign values to it and threw error because i set attributes to "private". Setting them "public" solved it for me.

Can't believe that was the error...