I am using PHPList V3.6.13 and it works perfect with PHP 7.4.33. However, when I upgrade to PHP 8.1.23 I only receive empty pages (logon, subscribe, etc.) If I revert back to PHP 7.4.33, everything works perfect again. I looked at the source code in the browser and there is nothing there either. I am using Firefox 117.0.1. I appreciate any help I can get.
This error is displayed in the source with error_reporting set to -1:
Fatal error: Declaration of sidebar::helloworld() must be compatible with phplistPlugin::HelloWorld($params) in /home/customer/www/riversidesnowbirds.com/public_html/lists/admin/plugins/sidebar.php on line 6