BPM Workspace Home Page (on login) shows a Blank Page

ISSUE:

While trying to access http://Hostname:Port/bpm/workspace page,a blank page was displayed.
As per Oracle Doc Id 1947645.1 we applied weblogic Patch16080294 to resolve the issue but unfortunately it didnt solve our issue.

Troubleshooting Steps:

We enabled trace 32 for detailed analyze of the issue:

Steps to Enable Trace 32:

Step 1) First login to Enterprise Manager as the Weblogic Administrative user.

http://Hostname:Port/em

Step 2) Once logged in, click on the Farm on the left of /em and then scroll down and click on SOA.

Step 3) With SOA expanded you see soa-infra, which you would then right click and select LOGS.

Step 4) Finally you have two options. i. View Log Messages, and ii. Log Configuration. Click on Log Configuration.

Step 5) When on the Log Configuration screen, by default the drop-down list is set to view Run-time Loggers.

Step 6) To enable TRACE 32 logs, select a particular branch of that oracle.soa.XX logger and modify it from NOTIFICATION:1 (INFO) to TRACE:32 (FINEST)

In our case below flags:

1)oracle.soa.services.workflow

2)oracle.soa.services.common

3)oracle.soa.services.identity

Step 7) Click APPLY once you have changed logger level.

Step 8) Logger changes occur immediately(no restart required) and can be seen in the managed server log on the file system.

Error Observed:

After enabling trace 32 below error was observed @
$DOMAIN_HOME/base_domain/servers/soa_server1/logs/soa_server1.out
<<
####<May 26, 2015 12:52:30 > <Error> <HTTP> <> <soa_server1 <[ACTIVE] ExecuteThread: '19' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <22916e5b548394ed:1e35bd83:14d8eb05919:-7ffd-000000000000e846> <1432633950996> <BEA-101017> <[ServletContext@1238133201[app:OracleBPMWorkspace module:/bpm/workspace path:/bpm/workspace spec-version:2.5]] Root cause of ServletException.
java.lang.StackOverflowError
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at sun.misc.Launcher$ExtClassLoader.findClass(Launcher.java:229)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:295)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:295)
at java.lang.ClassLoader.loadClass(ClassLoader.java:295)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at weblogic.utils.classloaders.GenericClassLoader.loadClass(GenericClassLoader.java:179)
at weblogic.utils.classloaders.FilteringClassLoader.findClass(FilteringClassLoader.java:101)
at weblogic.utils.classloaders.FilteringClassLoader.loadClass(FilteringClassLoader.java:86)
at java.lang.ClassLoader.loadClass(ClassLoader.java:295)
at java.lang.ClassLoader.loadClass(ClassLoader.java:295)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at weblogic.utils.classloaders.GenericClassLoader.loadClass(GenericClassLoader.java:179)
>>

Solution:

As “java.lang.StackOverflowError” error was observed in logs,it seemed that stack size parameter for soa server was too less.
In order to resolve the issue we increased stack size parameter for soa server from 256k to 512k.

Steps to change stack size parameter for soa server:

Step 1) First login to Weblogic Console as the Weblogic Administrative user.

http://Hostname:Port/console.

Step 2) Click Lock & Edit

Step 3) Select Servers-->soa_server1-->Configuration--> Server Start

Step 4) Edit Argument field as below:

Original:
-Xms2048m -Xmx2048m -Xmn1024m -Xss256k -XX:PermSize=512m -XX:MaxPermSize=1024m 

New Updated:
-Xms2048m -Xmx2048m -Xmn1024m -Xss512k -XX:PermSize=512m -XX:MaxPermSize=1024m

Step 5) Shutdown SOA server.

Step 6) Navigate to $DOMAIN_HOME/base_domain/servers/soa_server1/
mv tmp tmp_BKP
mv cache cache_BKP
While starting soa server above folder will be automatically created.

Step 7) Start SOA server

Step 8) Observe SOA server start up logs
You’ll know the SOA server is ready when the line “SOA Platform is running and accepting requests” message appears in the start up log(soa_server.out)..

Step 9) Access bpm workspace login page with below URL
http://Hostname:Port/bpm/workspace