My local site is running on 5.4.3. The cron works perfectly although I wasn't familiar with static functions but fixed it by creating a helper class. The cron is very complex so I have many functions which access all the different models and data writers in my add-on. My live site is running on 5.3.2-1ubuntu4.9. It uses apc. When I run the cron, it breaks right when it creates the helper class. I tried creating the class using new, XenForo_Model::create, and by using one of the other models to create the helper class. Each way works on my local site but not on my live site. Edit: No errors are showing up in the server error log. This line also seemed to be causing a problem. When it was uncommented it caused php to crash before the class was loaded even though it is in that class: PHP: $xfUserModel = XenForo_Model::create('Xenforo_Model_User');$dwPsnUser->set('username', $xfUserModel->getUserById($ufvWithPsnUser['ufv_user_id'])['username']); Again, works in local site, not in live.