Here is the error message that is in the error log:
PHP Fatal error: Uncaught TypeError: Unsupported operand types: int + string in /var/www/html/emr/sites/default/documents/smarty/main/%%1E/1EA/1EA5C8E9%%ajax_template.html.php:504\nStack trace:\n#0 /var/www/html/emr/vendor/smarty/smarty/libs/Smarty.class.php(1875): include()\n#1 /var/www/html/emr/sites/default/documents/smarty/main/%%61/61F/61F56BD5%%default.html.php(11): Smarty->_smarty_include()\n#2 /var/www/html/emr/vendor/smarty/smarty/libs/Smarty.class.php(1269): include('...')\n#3 /var/www/html/emr/interface/main/calendar/modules/PostCalendar/pnuserapi.php(589): Smarty->fetch()\n#4 /var/www/html/emr/interface/main/calendar/includes/pnMod.php(433): postcalendar_userapi_buildView()\n#5 /var/www/html/emr/interface/main/calendar/modules/PostCalendar/pnuser.php(112): pnModAPIFunc()\n#6 /var/www/html/emr/interface/main/calendar/modules/PostCalendar/pnuser.php(75): postcalendar_user_display()\n#7 /var/www/html/emr/interface/main/calendar/includes/pnMod.php(465): postcalendar_user_view()\n#8 /var/www/html/emr/interface/main/calendar/index.php(155): pnModFunc()\n#9 {main}\n thrown in /var/www/html/emr/sites/default/documents/smarty/main/%%1E/1EA/1EA5C8E9%%ajax_template.html.php on line 504, referer: https://ehr.wrigleyvillagepc.org/interface/main/tabs/main.php?token_main=e3HPSDFey4rufm2dkYr6ZTszas7xKHJU5N6ZGn5X
The server is running on PHP v 8.1.2-1 ubuntu2.11.
Seems there is an issue with the type hinting that is being used.
I am looking for that file now to find the bug.