Error after update

Version 3.x to 4 is less an upgrade than a migration - you'll have to rewrite the code for the site. See https://codeigniter4.github.io/userguide...e_4xx.html for details.

Hi, thanks for the reply.

It turns out there's a built in class called 'Generator', and I have a custom library with the same name. So that created the conflict.
I changed my library's name to 'My_generator' and changed the code accordingly and it works now, or at least shows a homepage.
However, you're right about the migration, I might get more errors like this as I test my code.