EBS 12.2 -- Blank page problem viewing concurrent out and logs, Hostname with Capital Letters, FNDWRR & node_info.txt

Recently encountered a problem on a new EBS implementation.
The problem appeared when the customer wanted to see the outputs and logs of the concurrent programs.
When they tried to open a concurrent log in the browser, a blank page was displayed.

In order to solve this issue, we did almost all the diagnostics, such as;

• Enabling sqlnet trace in the apps tier listener.ora
• Running "FS Diagnostic Test Program" with the parameter MODE=FULL 

The only error that we saw after running FS Diag Test Program was the following;

-- FNDFS did not return an error code 

-- FNDWRR did not create a debug logfile. 

-- FNDFS did not create a debug logfile. 

-- Displaying first 25 lines returned by FNDWRR.exe: 

-- BEGIN FILE ------------------------------------- 

-- END FILE --------------------------------------- 

-- ERROR: Unable to transfer file successfully! 

• Setting the profile "Viewer:Text" to have no value (remove 'browser')  and retesting viewing a log file. This was to bypass FNDWRR code process and pass the FNDFS output directly to the built-in viewer.

This was almost working. We could display the text output, but we could not display any other output formats such as pdf or xml.

• We did the tests documented in "How to Troubleshoot FNDFS and FNDWRR (Problems Viewing Concurrent Request Output) ( Doc ID 847844.1 )".  FNDWRR could display output from OS succesfully.
• Checked Apache logs  for CGI entries (FNDWRR is a CGI program) /access_log.* error_log.* etc.. We could only see HTTP 200 there. GET /OA_CGI/FNDWRR.exe?temp_id=796020226 HTTP/1.1" 200 - 
• Checked database alert log (just in case)
• Generated a Fiddler Trace and reviewed it. No errors
• Applied  "Patch 17075726:R12.FND.C - SUPPORT CONCURRENT MANAGER ON A SERVER CONFIGURED TO USE VIRTUAL HOSTING " , didn't fix.
• We disabled all the anti-virus and proxy checks in the client side, but issue remained.
• We created a SR (Oracle Support Service Request) , but it didn't help much. 
• Did the browser configurations below, but they didn't help at all.

Set up Oracle E-Business Suite to run through the 'Trusted Sites' zone with a 'Medium' Security Setting.
Tools -> Pop-up Blocker -> Pop-up Blocker Settings -> Allowed Sites
Tools -> Internet Options -> Privacy -> Pop-up Blocker: Settings -> Allowed sites
Selected (Checked) the following values:
Tools -> Internet Options -> Security -> <zone> (e.g. Trusted Sites) -> Enable Protected Mode
Tools -> Internet Options -> Advanced -> Enable 64-bit processes for Enhanced Protection Mode

THE CAUSE AND THE SOLUTION:

Well.. After all these diagnostics works, guess what we realized?

"The server name was written in capital-letters."  

Yes, the issue was caused by that.. 

The hostname of the EBS servers should not be written in capital letters. 

This is not supported and this issue is one of the causes of this support lack.. (note that, this issue is not documented, so that's why I m writing it :) )

The autoconfig and postclone are also affected by this problem, but there are workarounds for them. 

However; you can't get rid of FNDWRR (viewing concurrent log and out) problems, if you have a hostname with capital letters.

As for the solution, we updated $EBS_APPS_DEPLOYMENT_DIR/oacore/APP-INF/node_info.txt
and modified the lines which were including the hostname. 

We made all hostnames written in lower-case letters and the issue got resolved even without restarting anything.

Note:

txkFNDWRR.pl reads the node_info.txt and set the env variables accordingly. Using the $OA_HTML environment variable, txkFNDWRR.pl executes the FNDWRR, which in turn makes the conc log or out be displayed in browser screens.

I wrote this blog post to identify the diagnostics actions that need to be done while diagnosing such a problem and to show you the throubles that we may find ourselves in, if we have an unsupported configuration.