Getting errors after upgrading to PHP 8+

Installation
1

Just upgraded site from 9.2.x to 9.3.7 with PHP 7.4.14. Site runs fine after upgrade. After upgrading PHP from 7.4 to 8.2 or 8.3, most of the site runs fine except the Welcome Page, Extend Concrete5, and Update Concrete5 pages. When I click on these pages, I receive a " An unexpected error occurred. An error occurred while processing this request." These seem to be pages that try to contact Concrete5 servers and marketplace. It is appearing when trying to edit pages. I have looked at the php.ini extensions and modules and tried enabling different ones that were not already enabled.

For now I have moved back to PHP 7.4.14 with v9.3.7 running. No issues found with this setup.

Any suggestions on how to get PHP 8.2.25 or 8.3.13 working with v9.3.7?

2

Enable detailed error messages in the debug settings to reveal which lines are causing the issues. Most likely it’s undefined variables. So you need to initialize them before use like $var = null; or use the ?? null coalescing operator and a fallback value after trying to access the undefined variable.