I have raised a duplicate invoice and sent it to the customer by mistake. How do I correct this error and send the customer a credit note?

I'll walk you through on how to enter a credit note, sales124.

Before doing so, let's make sure that the Auto apply credit note option is turned off. This option applies the credit note to the oldest invoice. Here's how:

1. From the Gear icon, select Account and Settings.
2. Go to the Advanced tab.
3. Click the pencil (edit) icon on the Automation section.
4. Deselect the Automatically apply credits box.
5. Click Save, and then Done.

Afterwards, you're good to apply a credit note to the duplicate invoice.

1. Click the + New button.
2. Under Customers, select Credit note.
3. Enter your customer's name.
4. Fill out the required fields.
5. Click Save and close.

Please let me know if you need more help!