How to debug FinalizeError?

[unDEFER]

Hello! After long-long time of debugging, I just have decided 
InvalidMemoryOperationError in my program. But now my program 
after few hours of testing again crashes with "Finalization 
error".

What this error means exactly? I again did something wrong in 
destructor?
And how to debug it? I tried "break onFinalizeError" in gdb like 
"break onInvalidMemoryOperationError", but it says:

Function "onFinalizeError" not defined.

There are too few information about this error in documentation 
and forum, and I didn't find anything about it in wiki.

Thank you.