Variable {followup} in email template is not replaced

[p4rm3san]

When i select that order is in transit my client gets email with text {followup}

But when i add tracking number and client gets you order is sent they get good tracking.  But the status is not changed.

 

How i can change so when i send email in transit it would show correct info?

 

I tried this: https://www.prestashop.com/forums/topic/268322-solved-variable-followup-in-email-template-is-not-replaced/

But its 2014 information so the code changed since then and this haven't solved my problem i got error 500

[ksaan]

Hi,

Here is something you can try:

1) copy your file classes/order/OrderCarrier.php somewhere so you have a backup if it fails
2) modify file  classes/order/OrderCarrier.php line 131, replace

 '{followup}' => str_replace('@', $order->shipping_number, $carrier->url),

 by

 '{followup}' => str_replace('@', $this->tracking_number, $carrier->url),

 3) check if it works. If it does not, restore the file using the copy you have done at 1)

 This works for PrestaShop 1.7.4.2 . If your PrestaShop version is different, CHECK that line 131 looks the same and if it does you can try to apply this patch.