Hi,

In addition:

Also needed to change lines from 122:

// BOF qpbpp
if ($this->in_cart($products_id_string)) {
$this->update_quantity($products_id_string, $qty, $attributes, $discount_category);
} else {
$this->contents[$products_id_string] = array('qty' => (int)$qty, 'discount_categories_id' => $discount_category);
// EOF qpbpp

to include $discount_category_id instead of $discount_category thus:

// BOF qpbpp
if ($this->in_cart($products_id_string)) {
$this->update_quantity($products_id_string, $qty, $attributes, $discount_category_id);
} else {
$this->contents[$products_id_string] = array('qty' => (int)$qty, 'discount_categories_id' => $discount_category_id);
// EOF qpbpp


Following is correct file

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