Why is 500 error showing in PrestaShop product comparison?

Question

Prestashop

Hello!
After adding products to the list for comparison and going to the page , a 500 error is issued. When you turn on the display of server errors, the following is shown:

Notice: Trying to get property of non-object in /var/www/svddru/data/www/svdd.ru/cache/smarty/compile/ed/74/9d/ed749d

Notice: Undefined index: ajax_allowed in /var/www/svddru/data/www/svdd.ru/cache/smarty/compile/ed/74/9d/ed749d2af11acf978d4f6deb923e55d40a3b9d12.file.blockcart.tpl.php on line 86

Googling yielded no errors.
On line 86 of this file:

<?php if ($_smarty_tpl->tpl_vars['ajax_allowed']->value&&isset($_smarty_tpl->tpl_vars['blockcart_top']->value)&&!$_smarty_tpl->tpl_vars['blockcart_top']->value) {?>
                <span class="block_cart_expand<?php if (!isset($_smarty_tpl->tpl_vars['colapseExpandStatus']->value)||(isset($_smarty_tpl->tpl_vars['colapseExpandStatus']->value)&&$_smarty_tpl->tpl_vars['colapseExpandStatus']->value=='expanded')) {?> unvisible<?php }?>">&nbsp;</SPAN>
                <span class="block_cart_collapse<?php if (isset($_smarty_tpl->tpl_vars['colapseExpandStatus']->value)&&$_smarty_tpl->tpl_vars['colapseExpandStatus']->value=='collapsed') {?> unvisible<?php }?>">&nbsp;</SPAN>
            <?php }?>

2 days I can not figure out what's wrong, please help me to solve.

Answer 1

Clear the cache (Settings - performance), it will definitely help temporarily.
Also, switch smarty to "Recompile only when template files have been changed"