Backendless.Persistance.of(.class).find() call exception "Internal client exception"

I tried to use synchronous find() and programm called exception “Internal client exception”.
109-110 line in my code: http://pastebin.com/fY8e21gk
It happens only when I use synchronous find(). I can use asynchronous method for solve it but then I have another problem: http://support.backendless.com/t/problem-with-asynchronous-find-handleresponse-react-on-other-objects-collection
Regards,
Alexander

Make sure you use don’t use synchronous APIs on the main UI thread
Sync and Async API

I called Async method in main UI thread and then called sync method in first method’s handleResponse.

A callback handler is attached to the main UI thread

Thank you. I understood my mistake.
Regards,
Alexander