The following bugs are fixed:

• Behavior in some multi-store configurations fixed
• “Cannot add to cart” error for referrer, after a purchase with a discount had been made
• Discount usage limit for values over 1 worked incorrectly
• Complex combined discount rules (percent + fixed amount) were displayed wrong under some circumstances on the checkout

We strongly recommend to upgrade.

Find more information about the extension on the Refer a Friend Magento page.