JSP Error: fndvald.jsp Exception: java.lang.ExceptionInInitializerError java.lang.NoClassDefFoundError

ISSUE (observed after 11.5.8 to 11.5.10.2 APPS upgrade)
------

JSP Error:
--------------------------------------------------------------------------------
Request URI:/OA_HTML/fndvald.jsp

Exception:
java.lang.ExceptionInInitializerError 


subsequent requests result in 


Request URI:/OA_HTML/fndvald.jsp

Exception:
java.lang.NoClassDefFoundError 


SOLUTION
----------

I just found what the problem was -- finally!

After I ran the AutoConfig I spot checked the logfile for errors although it 
said that it completed with status 0 (success).  While I was checking the 
logfile I noticed the following warning message:

Unable to update GUEST_USER_PWD in database to GUEST/ORACLE - Cannot access 
application ORACLE password

Cause:  Application Object Library was unable access your ORACLE password.

I then changed the context file modifying the following tag to match our correct 
GUEST_USER_PWD:

vi /u01/app/applmgr/11.5/admin/OSID_midtier.xml

change:
            <password oa_var="s_guest_pass">ORACLE</password>
to:
            <password oa_var="s_guest_pass">GUEST</password>


## validate the password

SQL> select fnd_web_sec.validate_login('GUEST','GUEST') from dual;

FND_WEB_SEC.VALIDATE_LOGIN('GUEST','GUEST')
--------------------------------------------------------------------------------
Y


## re-run AutoConfig (the warning about GUEST_USER_PWD went away ...)

## comment out the following lines from jserv.properties and jserv.conf:
## refer to Note:309665.1 Oa_servlets/Hello World Throws Internal Server Error - Jserv is not up.
##

/u01/app/applmgr/product/iAS_115102/Apache/Jserv/etc/jserv.properties
#zones=mobile
#mobile.properties=/u01/app/applmgr/product/iAS_115102/Apache/Jserv/etc/mobile.properties

/u01/app/applmgr/product/iAS_115102/Apache/Jserv/etc/jserv.conf
#ApJServGroupMount /mobile       balance://OACoreGroup/mobile