Errors on Step 3 of 3 - Order Confirmation

Hi,

I hope someone can help. I am running Zencart 1.3.8a When going through checkout on my store the following is coming up underneath my basket contents:

Notice: Undefined index: tax_cart in /home3/bunnyzoe/public_html/includes/modules/payment/paypal/paypal_functions.php on line 662

Notice: Undefined index: tax_cart in /home3/bunnyzoe/public_html/includes/modules/payment/paypal/paypal_functions.php on line 690

Notice: Undefined index: tax_cart in /home3/bunnyzoe/public_html/includes/modules/payment/paypal/paypal_functions.php on line 725

Notice: Undefined index: tax_cart in /home3/bunnyzoe/public_html/includes/modules/payment/paypal/paypal_functions.php on line 730

You can still continue to confirm the order with PayPal but I know this is putting my customers off from doing so and one lady emailed me to make me aware of this error.

My technical girl looked at this for me but it hasn't been resolved. I have still had a handful of PayPal orders with these errors.

My web address is: bunnyzoescrafts.com

Any help or advice would be greatly appreciated.

Nikki x

When did this start happening?
On a normal uncustomized Zen Cart install, that doesn't happen.
Someone has turned on E_ALL error reporting to cause that to happen. That means someone has edited one or more files on your server to do that.
Who has access to your site? Why would they be changing things? Was someone altering checkout or payment files for some reason?
The probably likely started around the same time that someone made such changes.

Do you have good regular site backups?

You're using an old version of Zen Cart. Have you applied all the patches to it for the known security vulnerabilities in that version? If not, maybe you'be been hacked?