Database appears to be down while it is up.
When changing the Oracle version, Performance Analysis (StealthCollect) might not be able to connect to the database.
This might happen because the Oracle home or Oracle bit number (32 or 64 bit) might have changed.
On the middleware machine, please find the quest_sc_mw.cfg file in the following location depending on agent versions...
Applies to Performance Analysis version 3.x and 6.x and 7.0