I am having an issue using objects outside the main thread. As an example, I have this simple message class: http://hastebin.com/okuwanayak.php However, when I try to instantiate this on a thread other than the main thread, it throws a class not found exception. I am not trying to store it as a field or anything like that. I am serializing it to a string, successfully passing that string from the main thread to another thread, and then attempting to create a new Message object on the other thread. Both unserialize() as well as manually serializing and then using new Message(...)do not work. Message objects are used also in the main thread, but as you can see there are no static variables or other class-wide data. Is there something I am doing wrong that will allow the class loader to work as intended across threads? I tried adding extends \Threaded to Message, but that did not have any effect.