MySQL.Data: "Object reference not set to an instance of an object" when trying to Connect

I have a "Cron Service" that i've had running on our production server for over a year and a half.

It's a regular windows service which every minute connects to the DB, checks on one table whether there's something to do, and if so, does it. This is a server for a website that's not used a lot, so most of the time the service is completely idle.

A couple months ago, this service started throwing the following exception and dying:

MESSAGE: Object reference not set to an instance of an object.
SOURCE: MySql.Data
TARGETSITE: MySql.Data.MySqlClient.Driver CheckoutConnection()
STACKTRACE:    at MySql.Data.MySqlClient.MySqlPool.CheckoutConnection()
   at MySql.Data.MySqlClient.MySqlPool.GetPooledConnection()
   at MySql.Data.MySqlClient.MySqlPool.TryToGetDriver()
   at MySql.Data.MySqlClient.MySqlPool.GetConnection()
   at MySql.Data.MySqlClient.MySqlConnection.Open()
   at DBA.Connect() in D:\xxx\DBA.vb:line 21
   at CronService.TaskMailings.OnExecute() in D:\xxx\TaskMailings.vb:line 54
   at CronService.CronTask.ThreadExecute() in D:\xxx\CronTask.vb:line 99
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

The exception is clearly coming from inside the MySQL Library. Also, my function that calls it 开发者_开发百科is pretty simple:

    Public Shared Function Connect() As MySqlConnection
        Dim strConnString As String = WebConfigurationManager.AppSettings("ConnectionString")
        Dim DBConn As New MySqlConnection(strConnString)
        DBConn.Open()
        Return DBConn
    End Function

And the function where I'm calling DBA.Connect() (CronService.TaskMailings.OnExecute) is doing so with a "Using" statement, so the connection is getting closed, this shouldn't be a problem of connections being left open and getting exhausted (although it might, if there's a bug inside the MySQL library).

This is the connection string I'm using for the Service:

 server=localhost;port=13306;uid=xxx;pwd=xxx;database=xxx;Pooling=True;charset=utf8;

Any ideas what might be going on here? The strangest part is that this has worked for well over a year before it started happening out of the blue, and load to the server hasn't changed enough to justify it being a load problem, I believe.

EDIT: Some of the times it dies, it gives this other error message:

MESSAGE: error connecting: Timeout expired.  The timeout period elapsed prior to obtaining a connection from the pool.  This may have occurred because all pooled connections were in use and max pool size was reached.
SOURCE: MySql.Data
TARGETSITE: MySql.Data.MySqlClient.Driver GetConnection()
STACKTRACE:    at MySql.Data.MySqlClient.MySqlPool.GetConnection()
   at MySql.Data.MySqlClient.MySqlConnection.Open()
   atDBA.Connect() in D:\xxx\DBA.vb:line 21

Although the error message is pretty clear, like I mentioned before, we are releasing all connections, so this shouldn't happen. Any ideas?

I realize this is an old question however the issue lies in the mysql.data.dll

What version was this tested against?

I'm currently seeing this issue in 5.2.2.0 (and it doesn't happen in 5.0.1.0).

I'd suggest either down grading to 5.0.1.0 or upgrading to the latest and seeing if it still occurs.