Error
The item "X" exists in QuickBooks Online as a Product Category. QuickBooks Online does not allow Categories to be referenced on Transactions, or item names to be identical to Category names. You must change the name of your Category in QuickBooks Online before transferring this Transaction.
Business Validation Error: You can't use "X" because "X" already exists. To make this change, you'll need to give "X" a new, unique name or go to the Categories list to give the other "X" a different name.
Cause
Your product name in ConnectWise and QuickBooks Online has the same name. QuickBooks Online does not allow identical names to be referenced on transactions. The name of the Category or the product must be changed in order to batch
Examples
Resolution
Your category name in QuickBooks online is "X" and is the same as is the product name. Since they are the same, you will need to change either the category name in QuickBooks Online and/or the product name in ConnectWise PSA.This really depends on your preference of how you want this to look. The mapping, regardless of the name, should be mapped with "Category:Product".
Please review the following articles to resolve the issue.