SQL> drop user test cascade ;
ERROR at line 1:
ORA-00600: internal error code, arguments: [kkpo_rcinfo_defstg:objnotfound],, , , , , , , , , , 
1.) Apply the 126.96.36.199.2 PSU Patch: 11724916 or higher :
64-Bit (x64) Patch:11731184
2.) If available for our platform and version, download and apply Patch 10373381
3.) As a workaround, restore and perform a direct upgrade from 10.2.0.5 to the 188.8.131.52 release.