System.MissingMethodException When Sending Email using MailKit In Xamarin.Forms - xamarin.forms

Question

I am trying to use the MailKit library to send email in Xamarin.Forms. However, I am getting the following exception when execution hits the ConnectAsync() method:
System.MissingMethodException: string[] string.Split(char,System.StringSplitOptions) occurred
Has anyone encountered this before. I am unaware of any missing methods.
Following is my code in .net standard project:
using MailKit.Net.Smtp;
using MimeKit;
using MimeKit.Text;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
public async Task SendAsync(EmailMessage emailMessage)
{
try
{
var message = new MimeMessage();
message.To.Add(new MailboxAddress("Recipient", "xamapp#icloud.com"));
message.From.Add(new MailboxAddress("Sender", "xamapp.no.reply#gmail.com"));
message.Subject = "Test!!";
message.Body = new TextPart(TextFormat.Html)
{
Text = "Test message"
};
using (var emailClient = new SmtpClient())
{
await emailClient.ConnectAsync("smtp.gmail.com", 465, true);
emailClient.AuthenticationMechanisms.Remove("XOAUTH2");
await emailClient.AuthenticateAsync("username", "password");
await emailClient.SendAsync(message);
emailClient.Disconnect(true);
}
}
catch (SmtpCommandException ex)
{
Debug.WriteLine($"Error sending email: {ex.Message}");
Debug.WriteLine($"StatusCode: {ex.StatusCode}");
}
catch (SmtpProtocolException ex)
{
Debug.WriteLine($"Protocol error while sending email: {ex.Message}");
}
}

Answer 1

Sounds like your Xamarin.Forms project is pulling in mismatched .NET framework versions of libraries (probably the wrong MimeKit and/or MailKit framework versions).
Check to see which exact MimeKit and MailKit assemblies your build is pulling in from the nuget packages. In case you aren't familiar with how nugets work, each nuget can contain multiple copies of the library that is built for different frameworks.
For example, the MimeKit nuget has assemblies built for the following frameworks:
netstandard1.3
netstandard1.6
netstandard2.0
Xamarin.Android
Xamarin.iOS
net45
portable-net45+win8 (Profile7)
portable-net45+win8+wpa81 (Profile111)
And the MailKit nuget contains assemblies built for the following frameworks:
netstandard1.3
netstandard1.6
netstandard2.0
Xamarin.Android
Xamarin.iOS
net45
portable-net45+win81+wpa81 (Profile32)
Make sure that your project is pulling in the netstandard2.0 assemblies for both nugets and not a mix and match.