Hey! That warning is pretty common after a WordPress update. Basically, some old files didn’t get removed automatically. The Core.php file you mentioned is leftover from the previous version.
Here’s what I’d do:
- Backup everything first – your site files and database. Just in case.
- Check the file – it’s safe to delete if it’s not part of the current WordPress version.
- Delete it – you can use your hosting file manager or FTP to remove
wp-includes/SimplePie/src/Core.php.
- Test your site – make sure everything still works after deleting it.
If you’ve got a backup, there’s very little risk. Your site should run fine once the old file is gone.