A business validation error has occurred while processing your request. Business Validation Error: Select a product or service

We can tap our Intuit Developer Team to help us fix this error, chiragpatel7788.

The error you encountered usually occurs when a required field is left blank, or is filled in with wrong information. This is because QBO doesn't allow a zero or a negative amount in the line item when sent through the API. 

Our Intuit Developer Team can take a closer look at the error to ensure that it gets fixed immediately.

Please let me know if you need anything else. Thanks for dropping by.

In US Quickbook account my invoice sync successful . But in Canada Quickbook account it doesn't sync

Hello there, chiragpatel7788.

I want to make sure you get the right support you need so you can sync invoices to your QuickBooks Online Canada.

As mentioned by my colleague @SophiaAnnL, we do have a separate forum that can help you fix this type of error. They'll be the best experts to handle Busiiness Validation Errors.

You can raise your questions by visiting our Intuit Developer portal through this link: https://developer.intuit.com/us.

Should you have any other questions about QuickBooks invoicing, feel free to leave a reply below and I'll get back to you.