When opening a popup, the error “the requested content cannot be loaded please try again later” is displayed, where did you make a mistake?

Question

JavaScript

Good afternoon!
There was such a problem on WordPress 4.9.5, fancybox is connected without a plugin:
public function register_assets() {
wp_register_script( 'fancybox-scripts', ' https://cdnjs.cloudflare.com/ajax/libs/fancybox/3.... ');
wp_register_style( 'fancybox-style', ' https://cdnjs.cloudflare.com/ajax/libs/fancybox/3.... ');
}
wp_enqueue_script( 'fancybox-scripts', ' https://cdnjs.cloudflare.com/ajax/libs/fancybox/3.... ');
<?php dynamic_sidebar( 'header-popup-sidebar-phone' ); ?>
<?php dynamic_sidebar( 'header-popup-sidebar-email' ); ?>
<?php dynamic_sidebar( 'request-terms' );
On the page I insert the code - REQUEST TERMS OF COOPERATION
When pressed, a popup with the message: "the requested content cannot be loaded please try again later" falls out, but there is no content.
But when calling the other two popups, the popups open normally, without a message and with content.
Tell me where I could make a mistake?