you can try doing a manual update, so as long as you didn’t make any changes to the WordPress core files(if you did I suggest you take note of them and reapply after the upgrade), just head over to WordPress.org download the latest WordPress package and copy it over to your root folder on the server make sure you overwrite only the core WordPress files, leave the wp-content folder out of this, input your details to the wp-config.php file and that should probably sort this issue out for you.
PS. remember to back up your database and original WordPress folders before continuing.
