Fatal Error Seemingly Unrelated to any Plugins

Hello,

After upgrading WP and PHP, I am no longer able to create a new Post or New Page. Everything else with my WP site seems fine. I have done multiple FTP fresh installs of WP, deactivated all plugins, tried changing the PHP version, etc. Still, anytime I click “Add New” Page from the WP dashboard, I get the following error (note: I have tried re-uploading a fresh version of class-wp-rest-users-controller.php multiple times):

Fatal error: Uncaught Error: Class ‘WP_REST_User_Meta_Fields’ not found in /home/and2018/public_html/wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php:38 Stack trace: #0 /home/and2018/public_html/wp-includes/rest-api.php(281): WP_REST_Users_Controller->__construct() #1 /home/and2018/public_html/wp-includes/class-wp-hook.php(308): create_initial_rest_routes(Object(WP_REST_Server)) #2 /home/and2018/public_html/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters(NULL, Array) #3 /home/and2018/public_html/wp-includes/plugin.php(517): WP_Hook->do_action(Array) #4 /home/and2018/public_html/wp-includes/rest-api.php(577): do_action(‘rest_api_init’, Object(WP_REST_Server)) #5 /home/and2018/public_html/wp-includes/rest-api.php(535): rest_get_server() #6 /home/and2018/public_html/wp-includes/rest-api.php(2884): rest_do_request(Object(WP_REST_Request)) #7 [internal function]: rest_preload_api_request(Array, ‘/wp/v2/types?co…’) #8 /home/and2018/public_html/wp-includes/block-editor.php(638): array_reduce(Array, in /home/and2018/public_html/wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php on line 38

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