In my demo DB I tested it 3 times. Exporting TB via System>>exports>> resulted in a crash in all 3 cases. Interesting what is doing the D4IndexDelete in the backup process...

2017-03-20 16:11:07 8.3 2017-02-12 (build 83250202)

2017-03-20 16:11:37 AD Exporting company 6 Konsolidacija
2017-03-20 16:11:37 AD Exporting blocks
2017-03-20 16:11:37 AD Kopijos darymas baigtas
2017-03-20 16:11:37 AD Duration 6.19 seconds
2017-03-20 16:11:37 AD key: 4,10,14 4|2017-03-20>18 003 801 490 8;: 580 000 000.01|16:11:37.0
2017-03-20 16:11:37 AD D4IndexDelete found wrong record, now dumping index:
2017-03-20 16:11:37 AD new clean node at: 36617728 with 5 atoms and 19512 logical children
2017-03-20 16:11:37 AD key: 4,10,14 0|2005-06-20=58 006 801 488 :59 <80 000 000.04??88|8:37:28.0, daughter: 82723840
2017-03-20 16:11:37 AD new clean node at: 82723840 with 8 atoms and 4113 logical children