Recently I started getting ORA-00600 error, while I was trying to connect as
$ sqlplus sys as sysdba
SQL*Plus:Release 188.8.131.52.0 Production on Tue Jan 17 06:13:16 2017 Copyright (c) 1982, 2011, Oracle. All rights reserved. Enter password: ERROR: ORA-00600: internal error code, arguments: [kzsrgpw], , , , , , , , , , , 
This was caused due to a corrupt password file. Re-creating password file fixed the issue.
orapwd file=$ORACLE_HOME/dbs/orapw$ORACLE_SID password=syspassword entries=<#>
Metalink Doc ID 1073283.1