Cannot excess menu

Hi, thanks a lot for your great product.

I have a problem with menu. I cannot access the tab menu. If I try to access it in my console appearance – menu, then I get the following text (see below). All other themes work perfect and I do not get any errors. Could you help me?
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Проект ОМЕКОН portfolio-type Column (Mega Menu) ↑ | ↓ Изменить элемент меню
Текст ссылки Mega Menu Column Title (if you dont want to display a title just enter a single dash: “-” )

Атрибут title

link Target

Классы CSS (необязательно)

link Relationship (XFN)

Описание

Menu Style

Use as Mega Menu

This column should start a new row

Use the description to create a Text Block. Dont display this item as a link. (note: dont remove the label text, otherwise wordpress will delete the item)

Catchable fatal error: Object of class WP_Error could not be converted to string in /home/www/web354/html/Wordpress/wp-includes/formatting.php on line 703

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Best regards
Yulia