upgrading from 2.0.3 to 2.1.2

[eluser]dwlamb[/eluser]
I made a mistake earlier citing exactly what version I am upgrading from. It is 2.0.3 to 2.1.2. From the guides for upgrading, the steps are:

replacing the system folder (I had no customisations to begin with);
replacing application/config/user_agents.php;
replacing application/config/mimes.php

There is the step of updating ip_address columns to 45 characters for tables like ci_sessions but for my project tracking of IP addresses in a table is not employed.

Carrying out these upgrades breaks My site. All I get is a white browser window.

New to CI, I am not sure how to proceed, other than roll back to my previous installation.

Old Message:
I am attempting to upgrade CI from 2.1.0 to 2.1.2 and can not find a copy of version 2.1.1. Is it imperative that I upgrade incrementally?