ORA-06508 during nested execution

Question

There are 3 packages in database:
- package_A with package_A.proc_AA that calls package_B.porc_BB form package B
- package_B.proc_DD with procedure that calls procedure from package_C
- I change table that is using only in package_C
- I recompile all invalid objects. All package are VALID. My weblogic server is running. I check objects timestamp with this query (in result: no rows selected):
select do.obj# d_obj,do.name d_name, u.name owner, po.obj# p_obj,po.name p_name,
to_char(p_timestamp,'DD-MON-YYYY HH24:MI:SS') "P_Timestamp",
to_char(po.stime ,'DD-MON-YYYY HH24:MI:SS') "STIME",
decode(sign(po.stime-p_timestamp),0,'SAME','*DIFFER*') X
from sys.obj$ do, sys.dependency$ d, sys.obj$ po, user$ u
where P_OBJ#=po.obj#(+)
and D_OBJ#=do.obj#
and po.stime!=p_timestamp /*parent timestamp not match*/
and do.owner#=u.user#
order by 2,1;
Then I start using my applications. I call package_A.proc_AA via WLS and I get only one error: ORA-06508: PL/SQL: could not find program unit being called
This error comes from package_A.proc_AA when database try to execute package_B.porc_BB.
There are two way to resolve problem: WLS restart or recompile package_A.
Do you have any idea why this errors occurs and why WLS restart helps while errors comes from nested execution of package_B.porc_BB?
Are there any methods to prevent this error?
Do you have any ideas?
Thanks.

Answer 1

Your applications are probably using cached prepared statements, which have been
corrupted/invalidated by your changing the DBMS out from under your pooled
connections. If you are going to be doing that a lot, turn the WLS pool statement
cache off. Otherwise, you can clear the pool's statement cache from the console
when you do this.