OpenX versions before 2.8.10 got an issue with PHP 5.4, so if you can’t access Statistics on your OpenX server, there is a good chance you’ve hit this incompatibility.
Fixing it is pretty easy once you know the solution – either go to OpenX v.2.8.10 or edit the following files in order to remove the pointers:
<openx-root-folder>/lib/OA/Admin/Statistics/Delivery/CommonEntity.php – the block starting at line 292:
$oPlugin->mergeAds(&$this->childrendata[‘ad_id’]); //BEFORE
$oPlugin->mergeAds($this->childrendata[‘ad_id’]); //AFTER
<openx-root-folder>/lib/OA/Admin/Statistics/Delivery/CommonEntity.php – the block starting at line 322:
$oPlugin->mergeZones(&$this->childrendata[‘zone_id’]); //BEFORE
$oPlugin->mergeZones($this->childrendata[‘zone_id’]); //AFTER
<openx-root-folder>/lib/OA/Admin/Statistics/Delivery/CommonHistory.php – the function starting at line 160:
parent::prepare(&$aParams); //BEFORE
parent::prepare($aParams); //AFTER
Credits for the solution go to Aleksandr Cherniyh, his article openx-2.8 and php-5.4 and the comment with solution by Crow.