We're getting these sporadically.
Code
Fatal error: Uncaught TypeError: in_array(): Argument #2 ($haystack) must be of type array, false given in /var/www/html/ubbthreads/libs/user.inc.php:608 Stack trace: #0 /var/www/html/ubbthreads/libs/user.inc.php(608): in_array() #1 /var/www/html/ubbthreads/scripts/addpost.inc.php(668): user->check_group_join() #2 /var/www/html/ubbthreads/ubbthreads.php(286): page_addpost_run() #3 {main} thrown in /var/www/html/ubbthreads/libs/user.inc.php on line 608
Have you figured out what the cause might be?

The Stovebolt Geek
https://www.stovebolt.com/ubbthreads/ubbthreads.php

Server Information
UBB.threads Version 8.0.0
Release 20240826
Server OS Linux
Server Load 0.11
Web Server Apache/2.4.37
PHP Version 8.3.11
MYSQL Version 8.0.39
Database Size 1.82 GB