Q:

Why does opening a connection throw a distributed transactions error in MySQL? (.NET Connector)

I'm opening a connection to a local MySQL server and on the connection.Open() method it throws this error:

System.NotSupportedException: MySQL Connector/Net does not currently support distributed transactions.
  at MySql.Data.MySqlClient.MySqlConnection.EnlistTransaction(Transaction> transaction)
  at MySql.Data.MySqlClient.MySqlConnection.Open()

All I'm doing is this:
var connection = new MySql.Data.MySqlClient.MySqlConnection(ConfigurationManager.ConnectionStrings["Connection"].ConnectionString);
connection.Open();

The connection string in the app.config is 
<add name="Connection" connectionString="server=localhost;user id=userid;Password=password;database=dbname" providerName="MySql.Data.MySqlClient" />    

I don't know why it's trying to enlist the transaction, I haven't specified any transactions & I only have one MySQL server I'm connecting to

A:

Try adding Enlist=false to your connection string:
EDIT: from the MySQL Connector/.NET documentation, if you set AutoEnlist=false in the connection string it should work.
<add name="Connection" connectionString="server=localhost;user id=userid;Password=password;database=dbname;AutoEnlist=false" providerName="MySql.Data.MySqlClient" />    

It appears that certain versions of ADO.NET can default to automatically enlisting a connection into an existing transaction. See http://msdn.microsoft.com/en-us/library/ms254973.aspx for more detail, but I expect somehow somewhere ADO is confused into thinking that there's an existing transaction going on to some other db.

