Thanks for sharing your screenshots, @cpc-copierpc-com.

As an overview, when you import invoices with multiple line items, make sure each line entry has an invoice number, customer, invoice date, and other required details, just like in the sample spreadsheet.

I can see that the error occur because there are blanks on line entries from the second and fifth lines with invoice numbers: 2301118.

To fix this, I'd recommend removing those lines or filling those lines so it will go through. 

For your reference, check out this article to learn more about importing invoices in QuickBooks Online.

Get back to us here if you have additional questions. We're always around here to lend a hand of your importing concerns.