How to Fix Chrome Unable to Attach Files?

Fatal error: Uncaught Error: Class "WP_HTML_Tag_Processor" not found in /home/bigbossc/public_html/wp-includes/blocks/heading.php:27 Stack trace: #0 /home/bigbossc/public_html/wp-includes/class-wp-block.php(256): block_core_heading_render(Array, '\n<h2 class="wp-...', Object(WP_Block)) #1 /home/bigbossc/public_html/wp-includes/blocks.php(1051): WP_Block->render() #2 /home/bigbossc/public_html/wp-includes/blocks.php(1089): render_block(Array) #3 /home/bigbossc/public_html/wp-includes/class-wp-hook.php(308): do_blocks('<!-- wp:paragra...') #4 /home/bigbossc/public_html/wp-includes/plugin.php(205): WP_Hook->apply_filters('<!-- wp:paragra...', Array) #5 /home/bigbossc/public_html/wp-includes/post-template.php(255): apply_filters('the_content', '<!-- wp:paragra...') #6 /home/bigbossc/public_html/wp-content/themes/covernews/template-parts/content.php(26): the_content('Continue readin...') #7 /home/bigbossc/public_html/wp-includes/template.php(785): require('/home/bigbossc/...') #8 /home/bigbossc/public_html/wp-includes/template.php(718): load_template('/home/bigbossc/...', false, Array) #9 /home/bigbossc/public_html/wp-includes/general-template.php(204): locate_template(Array, true, false, Array) #10 /home/bigbossc/public_html/wp-content/themes/covernews/single.php(22): get_template_part('template-parts/...', 'post') #11 /home/bigbossc/public_html/wp-includes/template-loader.php(106): include('/home/bigbossc/...') #12 /home/bigbossc/public_html/wp-blog-header.php(19): require_once('/home/bigbossc/...') #13 /home/bigbossc/public_html/index.php(17): require('/home/bigbossc/...') #14 {main} thrown in /home/bigbossc/public_html/wp-includes/blocks/heading.php on line 27