Discount disappears after changing payment method

Question

we created coupon code, so that that coupon should not work if customer select "Cash on delivery" payment method.

customer will apply coupon in cart page & go to checkout and select Prepaid payment method and no issue here, he can see Discount as below image. [ -139]

Again customer will go back to "Payment information" step & he selects Cash on delivery and go to "Order review" step, he dont see any discount, thats fine.....

But customer become mad and again he go back to "Payment information" & select Prepaid payment method and come to "Order review" step, now he see the Devil that he dont see any discount....

This issue is happening only for new customers in site, for old customers there is no issue....

log errors in app/code/core/Mage/Checkout/Model/Type/Onepage.php

Notice: Array to string conversion in

$send .= $param . '=' . $value . "\r\n";}

Notice: Undefined variable: datasend in

$datasend .= substr($send, 5, -1);

Edit 2

Answer 1

You can add below code in your file at line no. 647 , you had forgot to define variable for $datasend,

$sendNewStr = '';
 foreach ($send as $param=>$value) {
    $sendNewStr .= $param . '=' . $value . "\r\n";
 }
 $datasend = '';
$datasend .= substr($sendNewStr, 5, -1);

Answer 2

Before digging into the overall code base, one key statement that you made above made me think that we should look at the overall Shopping Cart Price Rule:

• Existing users have no problems using the rule.
• New users are not seeing the discount.

Have you checked to make sure that in the Shopping Cart Price Rule, you rule has everyone selected?

Here's the same rule, but with all customer groups selected:

Hopefully this fixes the issue?

If this doesn't fix the issue, I'd recommend testing out the shopping cart price rule on a blank, fresh instance of the Magento 1.x site to see if it works there.

If it does work on a blank, fresh instance, it's likely a code modification or an extension conflict.

I'd recommend running a Magento code audit on the site to see if you have any core file changes or overrides, such as the one here: Free Magento Code Audit Tool

Answer 3

Try to perform a reindex and secondly, use native theme (rwd).