Checking PHP versions 7.1, 7.2, 7.3

1. Install the plugin PHP Compatibility Checker
2. Under tools run the checker
3. view report

Checking PHP versions 7.4, 8.0 download these apps

• PHP 8 Compatibility Check and Performance Tips
• or use vscode

Miscellaneous Internal Routines

• check for hacks
• Look for directories/files