tkyk

By the way, with the Notifications plugin enabled, your site health status page will look something like this:

Site health status

The Site Health Check shows information about your WordPress settings and items that may need your attention.
1 critical issue

Critical issues are items that can have a significant impact on your site's performance or security. Please resolve these issues with top priority.
Background refresh not working as expected

Background updates ensure that your version of WordPress is automatically updated when security updates are released.

     [OK] No version control system detected.
     [OK] This WordPress site does not require FTP credentials to perform updates.
     [ERROR] Some files cannot be written from WordPress:
         xmlrpc.php
         wp-blog-header.php
         readme.html
         wp-signup.php
         index.php
         wp-cron.php
         wp-config-sample.php
         wp-login.php
         wp-settings.php
         license.txt
         wp-mail.php
         wp-links-opml.php
         wp-load.php
         wp-includes/class-wp-styles.php
         wp-includes/class-wp-user-query.php
         wp-includes/l10n.php
         wp-includes/date.php
         wp-includes/php-compat/readonly.php
         wp-includes/class-wp-oembed.php
         wp-includes/images/w-logo-blue-white-bg.png
         ...

Thank you for your reply.

After disabling the Notifications plugin WordPress updates fine. I’ve also tried disabling other plugins and enabling only the Notifications plugin, but WordPress updates fail.