500 error after adding order from BO

[OswellSpencer]

When I add item new order from Back Office it throws me 500 error, and after reloading page I see error: 

 

Order is added correctly ( however without status update to "payment accepted" as it should ). 

In "var/logs" I see "Invalid product vars at line 158 in file classes/Link.php".

Thats the code:

 

Prestashop 1.7.6.1

Edited October 2, 2020 by OswellSpencer (see edit history)

[OswellSpencer]

UP

Delivery address is present in time of clicking "Create Order", and in database I see order with this field occupied correctly.

[OswellSpencer]

8 minutes ago, Crezzur said:

Please enable your error reporting, this way you will receive an error report instead of a 500 page.

I tried to go into debug mode, changed definse.inc.php to

/* Debug only */
if (!defined('_PS_MODE_DEV_')) {
define('_PS_MODE_DEV_', true);
}
 

In Admin Panel appears like debug mode is on, but it never appears like on the web. Tried clearing cache etc, without effect. Maybe there is some more cache somewhere...

[OswellSpencer]

1 hour ago, Crezzur said:

When you try to add a new order do you receive some additional warning/error?

Thats the only one.

[OswellSpencer]

I discovered that it is caused by "Mail Alert" module. Disabled it and it gone.