Unable to locate the specified class: Log.php (when upgrading PyroCMS)

[eluser]Unknown[/eluser]
Hi,

I hope you don't mind me posting this here...

I'm currently trying to upgrade my version of PyroCMS, which is built on CodeIgniter 2.1.x, and I'm receiving the following error when trying to access my website and admin area:

Unable to locate the specified class: Log.php

I've posted on the PyroCMS forum but no one appears to be able to help:
https://forum.pyrocms.com/discussion/248...ing#latest

I've run a search for the phrase, and everything appears to point to CodeIgniter.

As per the update instructions, I deleted the relevant folders, including CodeIgniter, and reuploaded them.
http://docs.pyrocms.com/2.2/manual/refer...1-to-2-2-0

Is anyone help to provide any assistance as to why I am seeing this issue?

[eluser]Unknown[/eluser]
Can anyone help with this?

I assume it has something to do with this file?
https://github.com/EllisLab/CodeIgniter/...Common.php