Upgrading from CI 1.7.3 to latest 2.2.0 ?

[eluser]Narf[/eluser]
There are upgrade instructions for each new version and you should gradually upgrade between them. Basically - yes, you have to follow the upgrade guide for 2.0.0, but also all the ones that are following it.

https://ellislab.com/codeigniter/user-gu...ading.html