Commerce 13 is ready to go

Hey Quan, we are currently building a new site on Commerce 12.15.1 and are a couple months away from Production.

My questions are;

1. How Production ready is will Commerce 13 be? eg. is this a CTP or RTM release?
2. Would you recommend immediately upgrading to Commerce 13?
3. Will there be a new Commerce 13 exam soon?

Cheers, Darren.

Hi Darren, I clean up your comments. Regarding your question:

1. Anything that is publicly released should be production ready. We did our best to ensure everything works as they should.
2. Yes, at least for testing purpose, to assert how much time you would need to spend on the upgrade. If you are using, for example, old promotion system then it should be easier to migrate to the new system then migrate. If you are using FindCommerce and/or ServiceAPI, you should wait for a little bit more. 
3. I don't know, I would expect there will be but it would take time to have more features worth testing for.

PART 1

"Commerce 13 contains a small migration step, which should complete within seconds, so data migration should not be of your concern. You are welcome to test it when it's released and get back to us if you need further assistance."

Hey Quan, we are having an issue with this migration step for serializableCarts. Could you spare some details on the migration step and what changes occurred to the serializable cart? It seems that the custom metadata properties now are no longer inferred by type but have a type and value. Example:

//OLD CART Metadata Property
"CWDTaxTotal": 6.71


//POST UPGRADE CART Meta Data Property
"CWDTaxTotal": {
    "$type": "System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089",
    "$value": 0
}

As you can see the type isn't even correctly set. Any information on what was changed and how we can successfully migrate the pre upgrade carts would be appreciated.

PART 2

To make progress with other parts of the upgrade we deleted the serializable carts. 

However there is an issue with serializable carts themselves. The ParentOrderGroup property on the ICart and IShipment are causing a circular reference error when using the json converter. This is preventing us from being able to view carts via ajax calls. Any suggestions to get