In probably Mambo times, we introduced a custom error handling code since PHP4 did not support exceptions at that time. As you noticed, we don't have 2008 anymore and PHP5+ does support exceptions, however we never removed our custom error handling. At least we moved most of it to the LegacyErrorHandlingTrait with Joomla 4. This issue is here to track the progress of converting everything to exceptions now. For this we introduced shouldUseExceptions() and setUseExceptions() in the trait in Joomla 6.0, so that you can switch between the old behavior and the new exceptions. The PRs linked below introduce this switch and a series of new exceptions. In a future major version we will then remove these switches again and only leave the exceptions as the finished solution.

• #48095 Introduce new exception classes
• #48096 Convert com_actionlogs, com_banners, com_cache
• #48097 Convert com_contenthistory, com_guidedtours, com_languages
• #48098 Convert com_messages, com_modules, com_privacy
• #48099 Convert com_installer, com_menus, com_redirect
• #48100 Convert com_scheduler, com_templates, com_workflow
• #48101 Convert com_contact, com_finder, com_newsfeeds
• #48102 Convert com_categories, com_content, com_fields
• #48103 Convert com_mails, com_tags, com_users
• #48104 Convert libraries
• #48105 Convert plugins