Today I have seen the net error in the alert.log;
kewastUnPackStats(): bad magic 1 (0xffffffff7a3bbdf8, 0)
After a working looking for this error at MOS. I see that the problem occurs where querying the (G)V$ACTIVE_SESSION_HISTORY view, as shown below;
select * from v$active_session_history;
It is the bug 8730312 and the solution is apply Patch 8730312, only avaliable for any enviroments. The best option is upgrade database if possible.
HTH – Antonio NAVARRO