url brocken / become /2F

I upgraded from CI4.1 or 2 (not sure) to CI4.3
I install a fresh installation and copy views, models controllers etc...

You installed v4.3.1 and copied your views, models controllers etc.
Did you change the Config files?
If you changed the Config, it might cause your issue.

But as I wrote, site_url() and base_url() use almost same code.
So I think it is not likely to be.

What if you install clean v4.3.1 and run?

PHP Code:

echo form_open('gestion/login/logincheck'); 


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