Welcome to the Community page, @rpineda2.
Based on the error message you’ve provided, I can see that you are attaching an unsupported format of a file into QuickBooks Online (QBO).
You can attach files to your transactions that are up to 20MB in size. QuickBooks also accepts a limited number of file types. That said, you’ll have to convert the file to supported file format to enable you to attach them to your sales transactions. Among them are:
- PDF
- JPEG
- PNG
- DOC
- XLSX
- CSV
- TIFF
- GIF
- XML
You'll also need to check the Attach to email button before sending your invoices. It's conceivable you send the invoice to your customer directly.
Once done, kindly send your invoice or bills again with an attachment on it.
Moreover, check out this article for your reference with recording an invoice payment in QBO. This completes the transactions and records in your books: Record invoice payments in QuickBooks Online
Should you need further assistance with your sales transactions, you can always click the Reply button. Have a great day!