Call to missing PHP file in MW 1.27

[faintaxis]

Hi,

I'm getting a "Fatal error: require_once(): Failed opening required '/srv/virtualhosts/wiki/html/includes/Wiki.php' (include_path='.:/usr/share/php:/usr/share/pear') in /srv/virtualhosts/wiki/html/extensions/PageAttachment/download/Download.php on line 33" when trying to open wiki page attachments.

Looks like wiki.php was deprecated pre-1.27. I'm not sure how to fix this issue.

Running MediaWiki 1.27 on Ubuntu server 14.04, PHP 5.5.9, MySQL 14.14 and Apache 2.4.7

Please Help!

Chris