So you went as far as chmod’ing your entire folder structure to 777 (very unsafe), you’ve hacked wp/wp-admin/includes/file.php
return new WP_Error( 'mkdir_failed_ziparchive', __( get_current_user() . ' Could not create directory. ('.$_dir.')' )...
to print out exactly what directory it cannot create and what user is trying to create the folder, everything is correct, yet it won’t create the fucking folder?
the issue might be your vsftpd configuration!
Go to /etc/vsftpd.con and make sure that you have this setting uncommented:
write_enable=YES
restart your vsftpd (sudo service vsftpd restart) and try upgrading again, you’ll want to hit that ‘Donate Bitcoin’ button if I saved your ass today.
Cheers