Process to Debug a Concurrent Request

If the program fails then set the following profiles at User level and rerun the program. Locate the Log and review for errors: 

FND: Debug Log Enabled to 'YES' 
FND: Debug Log Level to 'Statement' 
FND: Debug Log Module to '%'

Run the following query in Toad or SQLPLUS to review the request_id which failed:

SELECT to_char (timestamp,'DD-MON-YY HH24:MI:SS') "TIMESTAMP",  
       module, message_text, log_sequence 
FROM fnd_log_messages  
WHERE trunc(timestamp) = trunc(sysdate)  
AND process_id = (SELECT os_process_id  
                  FROM fnd_concurrent_requests  
                  WHERE request_id = &request_id)  
AND module not like 'fnd%'  
ORDER BY log_sequence;

References:
http://apurva-oracleappscrm.blogspot.com/2013/04/process-to-debug-concurrent-request.html