Not sure to migrate to CI4

@imabot,
> During the last days, I try to migrate one of my site to CI4.

I was never a fan of migrating and would be tempted to rewrite. Start with the Welcome_message and gradually introduce portions of the old site.

CI4 is different and best to forget the old CI3 single main class bad habits and slowly learn how to use multiple classes. Initially the learning curve is quite steep but it does get better.