Apex, version 3.2.1.00.10, on a 10.2.0.3-database is working fine for some time.
Then, while clicking the ‘application builder’ home-page, we got the ‘page not found’-error in the browser.
Logging of Apache shows:
mod_plsql: /pls/apex_schd/f HTTP-404 ORA-03113: end-of-file on communication channel\n
mod_plsql: Unable to reset state for mode 0: Err 3114 url=>/pls/apex_schd/f
Restarted the http-server and webcache: no result.
Configured the same apex on another application server, pointing to the same database: no result.
Allright, database alert-file shows:
ORA-07445: exception encountered: core dump [opidsa()+386] [SIGSEGV] [Address not mapped to object] [0x000000000] [] []
There were no changes (really, there weren’t…) in the past few days.
Points out to be a bug in 10.2.0.3 (with any version of Apex): bugnr 5745817 :
“Implementing regular flushes of the shared pool can prevent the problem from occurring.
The problem is fixed in 11g via non-published bug:5648872 and the fix is included in 10.2.0.4.” (note 418531.1)
The patch is also available: 5648872
For the time being, ‘alter system flush shared_pool’ is fine for me, until we upgrade to 10.2.0.4 (or 11gr2 of course…
).

Thanks for the suggestion.
We were facing the same issue and your suggestion helped us to solve this issue.
Thanks once again.
Best Regards,
Vinodh