How do I diagnose this exception?

[Matthew Jew]

Hello!

I am continuing my project of converting my app from Valentina 2.5.8  
to 3.5.2.

My app runs now (with the few small changes I needed to make to have  
it work under 3.5.2).
However, it seems to throw an exception every time I add about 3,000  
to 4,000 records.
It is not consistent about when it throws the exception.
(Meaning I can run the app on the very same data, importing from the  
same file, and it will
  sometimes not throw the exception at all. It will also throw it, but  
on a different record each run.)

Here is the exception:

terminate called after throwing an instance of 'fbl::xInternalError'

This is the stack at the time of the exception.

#0	0x013d522c in __tcf_0
#1	0x01009854 in cxa_atexit_wrapper
#2	0x90014d5c in __cxa_finalize
#3	0x90014c44 in exit
#4	0x9012d804 in abort
#5	0x94cb1078 in __gnu_cxx::__verbose_terminate_handler
#6	0x94caec08 in __gxx_personality_v0
#7	0x94caec6c in std::terminate
#8	0x94caef30 in __cxa_rethrow
#9	0x01160120 in fbl::AddRecordToIndex_OneField
#10	0x011602dc in fbl::Table::AddRecordToIndex
#11	0x01164a34 in fbl::Table::AddRecord_WithOut_Triggers_ex
#12	0x01163a10 in  
fbl::Table::AddRecord_WithOut_OnEachStatement_Triggers_ex
#13	0x011635d0 in fbl::Table::AddRecord
#14	0x007395b0 in -[ArticleDBManager2 importOneArticleFile:] at  
ArticleDBManager2.mm:1584
#15	0x0073a40c in -[ArticleDBManager2  
importOneDayFolder:statusCountVar:statusLimitVar:stopProcessVar:] at  
ArticleDBManager2.mm:1818
#16	0x0079b778 in -[ArticleMultiManager2  
importDay:statusCountVar:statusLimitVar:stopProcessVar:] at  
ArticleMultiManager2.mm:615
#17	0x00087488 in -[UpstreamServer  
getAndProcessUpstreamArticleSetFromUpstreamFolder:toLocalFolder:] at  
UpstreamServer.mm:1853
#18	0x00084500 in -[UpstreamServer replicatorTask] at  
UpstreamServer.mm:741
#19	0x00035a14 in -[PVReplicatorModelObject replicatorTask] at  
PVReplicatorModelObject.m:967
#20	0x92bf4118 in forkThreadForFunction
#21	0x9002bd08 in _pthread_body

How can I get more information about the exception and what is causing  
it?

- Matthew