There might be a plugin or theme which is loading Javascript/AJAX improperly in your admin area. You can check admin area browser console to see if there is any error/warning there. If you have WP_DEBUG_LOG enabled, see if there is any error/log.
Also, you can disable the plugins that affect the admin UI (e.g. security plugins, admin dashboards) and then, try updating again and see if the error persists.
You can disable any caching plugin, if there is any, and try to see if it resolves this issue and dont forget to Clear your browser cache.
There are a few additional steps you can take to resolve this issue.
Firstly, ensure there are no file or folder permission conflicts on your server, as incorrect permissions can prevent the update process from running smoothly. Check that your wp-content folder has permissions set to 755 (for folders) and 644 (for files).
Additionally, it could be a connectivity issue between your WordPress site and the update server. To rule this out, verify that your server can reach ww.wp.xz.cn by checking with your hosting provider or running a cURL test.
Lastly, if there are still no results, try re-uploading the WordPress core files manually. Simply download the latest version of WordPress, extract it, and overwrite all files except the wp-content folder and wp-config.php file. This can help refresh and fix any corrupted files causing the issue.
