Fix "Missing a temporary folder" in WordPress 2.7

As I was writing my article about the installation process of Openfire, I've tried to upload a file but got an error message instead of my file :(

Because I wasn't able to upload a file, I've done a quick google search and found this blog entry. The problem was easy to fix: the upload_tmp_dir is not set in php.ini. After adding:

php_admin_value upload_tmp_dir /var/www/domain/php/upload

to my Apache Vhost-configuration and doing a reload, everything worked as expected.

Thanks, Dwight Jack!