dapper rainbow MissingMethodException

Question

Why do I get this exception? The code isn't the same but close to the 'demo' https://gist.github.com/1599013

Exception: MissingMethodException

Desc:

Method not found: 'System.Collections.Generic.IEnumerable1<System.Object> Dapper.SqlMapper.Query(System.Data.IDbConnection, System.String, System.Object, System.Data.IDbTransaction, Boolean, System.Nullable1, System.Nullable`1)'.

Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Mail;
using Dapper;
using System.Data.SqlClient;
using MySql.Data.MySqlClient;

namespace daconsole2
{
    class Program
    {
        class Product
        {
            public int Id { get; set; }
            public string Name { get; set; }
            public string Description { get; set; }
            public DateTime? LastPurchase { get; set; }
        }

        // container with all the tables
        class MyDatabase : Database<MyDatabase>
        {
            public Table<Product> Products { get; set; }
        }
        //*/
        static void Main(string[] args)
        {
            var cnn = new MySqlConnection("uid=name;pwd=pw;Port=3306;database=test");
            cnn.Open();
            var db = MyDatabase.Init(cnn, commandTimeout: 2);
            //if(false)
            db.Execute(@"create table Products (
Id int primary key,
Name varchar(20),
Description TEXT,
LastPurchase datetime)");
            var productId = db.Products.Insert(new { Name = "Hello", Description = "Nothing" });
            //var db = cnn;
            Console.ReadKey();
        }
    }
}

Answer 1

We had this same problem, and it turned out to be that some of the projects in the solution were referencing different versions of Dapper. For example, one project used a runtime version that showed v4.0.30319 in the Properties window. Another project had a Dapper runtime version of v2.0.50727 (.NET 3.5).

As soon as I set them all to the v2.0.50727 version, this error went away.

*It should be noted that they both show File Version 1.12.0.0, so this is not a reliable way to tell them apart.