ORA-00600: internal error code, arguments: [qmxtrScalarIsRewritable:dft], [], [], [], [], [], [], [] and ORA-07445: exception encountered: core dump [kgghstfel()+4] [SIGSEGV] [Address n ot mapped to object] [0x000000018] [] []

I faced the following errors in the alert log and the developers were not able to view the DDL from the JDeveloper and toad for any user in the database.

The Call stack for the trace file for error ORA-07445 :


qmxtrxq()+464        CALL     qmxtrxq()            000000000 ?
                                                   FFFFFFFF7FFED090 ?
                                                   000000001 ?
                                                   FFFFFFFF7AD3B698 ?
kgghstfel()+4        PTR_CALL 0000000000000000     000000000 ? 106843EF0 ?
                                                   106843C10 ?
                                                   FFFFFFFF7D500200 ?
                                                   000000000 ?
                                                   FFFFFFFF7C73C000 ?
qmtLookup()+80       CALL     kgghstfel()          000000000 ? 3B26F7628 ?
                                                   000000000 ? 000000000 ?
                                                   000000002 ? 3B26CD118 ?
qmtRemoveRef()+76    CALL     qmtLookup()          10669E678 ? 3B26F7628 ?
                                                   3B26CD6D0 ? 000000029 ?
                                                   00010581D ?
                                                   FFFFFFFF7C026620 ?
qmxtrCleanRewriteCt  CALL     qmtRemoveRef()       10669E678 ? 3B2633A18 ?
x()+44                                             000105800 ? 10581D000 ?
                                                   3B26CD118 ? 000000000 ?
qmxtrxopn()+680      CALL     qmxtrCleanRewriteCt  FFFFFFFF7FFE5BC8 ?
                              x()                  FFFFFFFF7FFE5B18 ?
                                                   FFFFFFFF7FFED090 ?
                                                   10669E338 ? 10669E000 ?
                                                   00010669E ?
qmxtrxopt()+156      CALL     qmxtrxopn()          FFFFFFFF7B9C0118 ?
                                                   FFFFFFFF7FFED090 ?
                                                   000008000 ? 000000000 ?
                                                   002000000 ? 000004004 ?
qmxtrxq()+256        CALL     qmxtrxopt()          FFFFFFFF7B9C0118 ?
                                                   FFFFFFFF7FFED090 ?
                                                   000000000 ? 000000003 ?
                                                   FFFFFFFF7B9DFB20 ?
                                                   FFFFFFFF7B9DF718 ?
qmxtrxq()+464        CALL     qmxtrxq()            0FFFFBC00 ?
                                                   FFFFFFFF7FFED090 ?
                                                   000000000 ?
                                                   FFFFFFFF7B9C0118 ?
                                                   FFFFFFFF7B9DF718 ?
                                                   000000000 ?

after investigation i found similar bugs on metalink and they were related to XML DB.i decided to remove the XML DB from the database as it was not being used.

The steps to remove XML DB:
XDB Removal

The catnoqm.sql script drops XDB.

SQL> spool xdb_removal.log
SQL> set echo on;
SQL> connect / as sysdba
SQL> shutdown immediate;
SQL> startup
SQL> @?/rdbms/admin/catnoqm.sql
SQL> spool off;
you can refer to document :
 How to Deinstall and Reinstall XML Database (XDB) [ID 243554.1]


after removing the XML database i found many invalid objects in the sys user which impaced the database.i resolved those issues by running the following scripts:


Catalog - creates data dictionary views.
Catproc - create in built PL/SQL Procedures, Packages etc


running catalog and catproc will make your packages/procedures invalid. You will have to recompile them. 
You can use utlrp.sql which you can find in $ORACLE_HOME/rdbms/admin




after finishing the above statements i found no invalid objects in sys schema ,but the following error appeared:

Errors in file /app/home/oracle/admin/DEVDB/bdump/devdb_j000_29009.trc:
ORA-12012: error on auto execute of job 42568
ORA-04063: ORA-04063: package body "EXFSYS.DBMS_RLMGR_DR" has errors
ORA-06508: PL/SQL: could not find program unit being called: "EXFSYS.DBMS_RLMGR_
DR"
ORA-06512: at line 1
 has errors
Mon Nov 28 19:42:33 2011
Errors in file /app/home/oracle/admin/DEVDB/bdump/devdb_reco_11767.trc:
ORA-02019: connection description for remote database not found
Mon Nov 28 23:40:44 2011

 i resolved the following error by doing the following oracle note:

How To Install and Uninstall Expression Filter Feature or EXFSYS schema [ID 258618.1]

The database is up and running now with no problems.