Oracle 11.2.0.4 Internal error (ORA-600[kxfpqsod_qc_sod]) detected

This error seems to be generated by DEFAULT parallel server settings on small tables.
After some investigations with Oracle Support we get the following solution:

Run PXHCDR.SQL: Parallel Execution Health-Checks and Diagnostics Reports (Doc ID 146040.1) to extract objects with DEFAULT parallel settings and tables that have different DOP settings from their indexes.


Any table less than 1 GB in size should be with DEGREE=1. You can find all the tables and degree in "DOP" html.

Action Plan
__________

1. Make all tables whose size < 1 GB as : Alter Table <schema.table_name> NOPARALLEL;
2. Keep Tables and corresponding index same degree, i.e. if a TABLE has DEGREE 1, then make its all Index as DEGREE 1 OR if a table has DEGREE 4, keep all its Index as DEGREE 4
3. Do not leave any object with DEGREE DEFAULT. Have a correct integer value. As a practice, Tables > 1 GB < 4 GB DEGREE 2, while Tables > 4 GB keep DEGREE 4

Statement to alter degree:

Tables : Alter table <schema.table_name> PARALLEL (DEGREE N) ; ==========> N is the integer value, 2 or 4 or DEFAULT etc.
Index : Alter index <schema.index_name > PARALLEL (DEGREE N) ;

You can view DEGREE for Tables and Index in DBA_TABLES and DBA_INDEXES respectively.