This error message occurs when syncing a transaction from Procore to QuickBooks but the product/service that it is going to in QuickBooks does not have a linked income/expense account (depending on the type of transaction that is syncing).
Here is an example of this error message:
To resolve this error message, the product/service must be edited in QuickBooks to have a linked income/expense account, and then the transaction can be synced to QuickBooks.
Here is an article from Intuit for more information on products/services:
https://quickbooks.intuit.com/learn-support/en-us/help-article/small-business-processes/add-product-service-items-quickbooks-online/L9yEFWaNM_US_en_US
In order to solve this, go to your product/service list in QuickBooks and then click to edit the product/service that is giving the error:
When editing the product/service, make sure that an income and expense account is selected (as per the screenshot)
If these dropdowns are not appearing, make sure that 'I sell this product/service to my customers' and 'I purchase this product/service from a supplier' checkboxes are ticked, then you can select the desired income/expense account for the product/service.
Once this is selected, the invoice can be resynced from Procore to sync to QuickBooks. See this page for how to resync the invoice
https://support.smoothlink.net/how-to-resync-an-invoice-from-procore-to-the-accounting-system