У вашего броузера проблема в совместимости с HTML5
On 6th December 2018, WordPress 5.0 was released. This version of WordPress replaces the old WYSIWYG editor with the block editor named Gutenberg.
Should you update? Is it safe to update? In this video I will go through the update process, with a simple test you can do to make sure your website, plugins and theme are ready for the WordPress 5.0 Gutenberg update.
https://ezseonews.com