There are several different warning messages you may have received when you attempted to sync your invoices to Quickbooks:

This is a message from QuickBooks stating there is a document in QuickBooks (either an invoice or credit memo) already with the invoice number. If it's an invoice number for a different client (created in QuickBooks), the invoice in 17hats will need to be redone with a new invoice number. If it's a credit memo, you should be able to edit the credit memo in QuickBooks and change the number.

Forcing an invoice to sync from 17hats will overwrite whatever QuickBooks Online has in their system.

This is an issue on QuickBooks Online's side, and is usually temporary.  Please try again later, and if the issue persists, please contact us at support@17hats.com.

This message suggests you are trying to create a product that already exists in QuickBooks. This may mean that you have duplicate products and services in Quickbooks.  Please try using a different name for this item.

This error means that there was an issue in the connection between 17hats and Intuit. Intuit Data Services failed to respond to 17hats within a set time. This can result from Intuit experiencing an increased amount of traffic or issues with their servers. Unfortunately, there is nothing the 17hats team can do about this issue, so please be patient and try again at a later time.

This error means that an item in the Invoice has too many characters. For example, Quickbooks only supports a maximum of 4,000 characters for a line item entry. If a line item exceeds this character count, you'll see the error above in the Quickbooks "Import Invoices" screen in 17hats:

* This feature may not be available on all plan types.