Here I list all the sort of dumb things that were done to fix issues.
a $_SESSION[“variable”] was undefined for php 5.2, why did reuploading the file to cpanel,fix this bug, is there a cache for php 5.2?
There are a few possible reasons why reuploading a PHP file to cPanel may have fixed an issue with an undefined session variable in PHP 5.2:
PHP sessions are stored on the server-side, either in files or a database. It’s possible reuploading the file cleared out any stale session data that was causing the issue.
cPanel may have been caching old versions of the PHP scripts. Reuploading forced it to use the new code. PHP 5.2 does not have opcache enabled by default, but cPanel could still cache scripts in memory.
If register_globals was enabled in the old PHP version, session variables may not have been available in the global scope by default. Reuploading with a proper session start could have fixed it.
There may have been an error in the old file that was preventing sessions from starting properly. Reuploading replaced it with a working version.
If the site was load balanced across multiple servers, reuploading may have pushed the code to all servers so they were using the same new code.
So in summary, reuploading likely cleared out any cached old code or session data, and replaced it with a proper working version that had sessions configured correctly. The exact reason depends on the specific PHP/cPanel configuration and code in use.
Adding a space to fix bugs in code.