ORA-600 [kkoipt:incorrect pwj].
There are some ORA-600 which can be easily googled, and there are others which are pretty difficult to find. This is the case. M.O.S reports this ORA600 to be related to a bug (9929660) on the 11.2 platform and which is fixed on 12.0.
Recently this error showed up on a Windows 2003 platform with Oracle 18.104.22.168.0. After deciphering the almost cryptic related trace and dump file and diagnosing after the possible environment causes. I found out this error was triggered at one of the internal performance maintenance task, and the root cause was related to a lack of processes in the database.
This error was fixed in this particular case and platform by increasing the value of the PROCESSES instance parameter.
The only one who has the authority to decode and understand the trace files related to the Oracle internals is Oracle support ... unless you are willing to take the quest of reading them and trying to understand them as your last resource.
The information provided in this post is only for information purposes, and to share a very particular experience in my local environment. The only one authorized to provide a diagnose about an ORA-00600 is Oracle Support Services.