I sometimes get the following error
<b>Fatal error</b>: Exception thrown without a stack frame in
<b>Unknown</b> on line <b>0</b><br />
What does this mean?
When we see these, they're typically from our custom session handler.
In my experience that error is almost certainly in a piece of your code that is run after the main execution of the program is complete. So places to check are shutdown functions (things registered with register_shutdown_function()), custom session handlers and object destructors. Basically any piece of code that can be called after the official execution of your script is complete and clean-up is occuring.
Adam Ashley