Issue : Unable to integrate the Customer into QuickBooks Online from Salesforce; even though, the Salesforce Account does not exist in QuickBooks as a Customer.

Reason: A Vendor, or Contractor, or an Employee exists in QuickBooks with the same name as Salesforce Account, hence Customer will not be created.

Error in DBSync Logs:

<Error code="6240" element="">

<Message>Duplicate Name Exists Error</Message>

<Detail>The name supplied already exists. : Another customer, vendor or employee is 

already using this name. Please use a different name.</Detail>

</Error>

Error in the Browser:

Account in Salesforce (Customer/Vendor Test):

Vendor/Contractor already exists in QuickBooks with the same name:

Solution:

1. Rename the Vendor/Employee name in QuickBooks other than Salesforce Account name.
2. Rename the Account name in Salesforce other than QuickBooks Vendor/Contractor/Employee name.
3. Delete the Vendor in QuickBooks if it is not required.

Renaming the Account name in Salesforce as Customer/Account Testing:

Customer has been created in Quickbooks: