Message Errors

[bensan]

Can anybody tell me why Im getting these messages;

Message: Object of class CI_Loader could not be converted to string
Message: Object of class CI_Loader could not be converted to string
Message: Object of class CI_Session could not be converted to string
Message: Object of class CI_Session could not be converted to string
Message: Undefined variable: date
Message: Undefined variable: openCategory
Message: Undefined variable: date
Message: Undefined variable: openCategory
Message: fopen(Advert/ben/National.php): failed to open stream: No such file or directory
Message: fwrite() expects parameter 1 to be resource, boolean given
Message: fclose() expects parameter 1 to be resource, boolean given
Message: fopen(advert/ben/national.php): failed to open stream: No such file or directory
Message: fwrite() expects parameter 1 to be resource, boolean given
Message: fclose() expects parameter 1 to be resource, boolean given
Message: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\system\core\Exceptions.php:271)

I suspect it has something to do with CodeIgniter version upgrade.

Currently - const CI_VERSION = ‘3.1.9’;
XAMPP version 7.2.3

Has anybody got an easy fix?

[bensan]

UPDATE 09/12/22
I tend to believe that the problem is related to CodeIgniter not being installed properly, although pages will display, the dynamics of CI will not work.

I have decided to download & install the latest XAMPP.

I have downloaded the latest CI & intend to install the same. But as usual I can not understand the CI User-Guide. CI does not appear to have an instalation engine the same as XAMPP.

Are there any experts who can guide me?

(1) Where & how should I install CodeIgniter into XAMPP? I read in one tutorial (not CI User-Guide) to “unzip the CI file into the htdocs folder”. Is that correct?

(2) Should I create a skeleton project in CodeIgniter4 then copy & paste my existing CodeIgniter3 Controller, Model, & View files into the skeleton project?
or
(3) Should I add CodeIgniter4 to my existing CodeIgniter3 project? How to do that?
but
(4) If I add anything to an existing & faulty installation the problems will not disappear.