ERRT006: Customer '....' already exists in MYOB as Supplier.
This happens when a customer fails to export into MYOB because there is a Supplier Card that has the same Card ID.
In MYOB, Client and Supplier Cards are stored in separate lists, but the Card ID must be globally unique, therefore MYOB won't accept a Client and a Supplier sharing the same Card ID.
One possible cause for this problem is that a Company in Connectwise is acting as both: a supplier and a client, which is determined by the existence of purchases and invoices linked to the same company.
If it is a common scenario that companies act like both clients and suppliers, then you can configure the integration tool to add a prefix to all exported Supplier Cards, while no prefix will be added to Customer Cards, thus eliminating the clash of Card ID.
Start by opening the Configuration screen of the Integration Tool. Then open the Export Settings.
The image below highlights the setting you need to work on.
The setting is the Supplier Card ID Prefix. It will be empty by default.
Set a value to work as a prefix for all of your supplier cards. Preferrably in Capital and as a single character. For example, an "S".
What this will do is precede all Supplier Card IDs with this "S", whereas Customer Cards will not have any prefix.
In this example, we will work with the Company ACME in Connectwise, for which the Account ID is "ACME".
With the setting explanined above, this company will be exported as a Supplier Card like this (notice the prefix in the Card ID):
However, if the same company gets exported as a Customer Card, it will be like this:
That way, the clash in Card IDs will be eliminated.