I am getting an undefined error while importing bill

Hello there, accounts2-xtreme.

Let's work together to ensure that your bills are successfully imported into QuickBooks Online.

When preparing your CSV (or Excel) file to import bills, keep in mind that the following mandatory columns must be included:
 

• Bill no.
• Supplier
• Bill Date
• Due Date
• Account
• Line Amount
• Line Tax Code

Also, there are certain capabilities and limitations that you need to know to successfully upload your bills. You can check out this article for more details: Import your bills in QuickBooks Online.

I've also added this resource as a future reference: Enter and manage bills and bill payments in QuickBooks Online.

Let me know if you still have follow-up questions about importing bills. I'll be here to check on your response. Have a wonderful day!