ORA-00600: internal error code, arguments: [kcratr_scan_lastbwr]

Launch SQL Plus from Oracle\bin folder ( not from Client folder)

SQL> conn sys/sys as sysdba
Connected to an idle instance.


SQL> startup mount;
ORACLE instance started.

SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-00600: internal error code, arguments: [kcratr_scan_lastbwr], [], [], [],
[], [], [], [], [], [], [], []


SQL> shutdown immediate;
ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.

SQL> startup mount;
ORACLE instance started.
Database mounted.

SQL> recover database;
Media recovery complete.

SQL> alter database open;
Database altered.

SQL> conn scott/tiger@orcldb
Connected.

Your database is good to go now, You better take a backup of your system.