FLEX_SOURCE,0: The OCI function OCIStmtFetch2 returned status -1. Error code: 600, Error message: ORA-00600: internal error code, arguments: , , , , , , , , , , , . (CC_OraStatement::fetch, file CC_OraStatement.cpp, line 1,599)
It's better to move this question to Database
You can use ORA-600/ORA-7445/ORA-700 Error Look-up Tool (Doc ID 153788.1)
In addition to what GokhanAtil suggest. I'll also suggest you contact Oracle support and submit an SR.
There isn't much we can do with the details you provided.