Extending an existing web application using Codeigniter4

There is no config to disable Session in CI4. Because it is used when it is needed.
So basically, if you don't use CI4 Session, it does not work.

I don't know this is good for you, but we can use CI4 session in plain PHP if there is no conflicts.
https://github.com/kenjis/ci4-session-in-plain-php

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