How to find the error when nothing is logged in the logs in R12.2

 "You have encountered an unexpected error. Please contact the System Administrator for assistance"

We can trace the error from the database as well. Please do the following to figure out the cause from tables.  

A. 

To Enable FND debug: 

Navigate Responsibility: System Administrator > Profile => System 

a. Find the FND profile options for User who is submitting the process to debug. 

User: User submitting the process 

Profile: FND:%Debug% 

b. Set the following Profile values at the user level 

FND: Debug Log Enabled :Yes 

FND: Debug Log Filename : NULL 

FND: Debug Log Level : STATEMENT 

FND: Debug Log Module : % 

c. Save. 

B. 

Get the current log sequence in the FND table. 

select max(log_sequence) from fnd_log_messages ; -- start 

C. 

Reproduce the issue 

D. Get the sequence in the FND log 

select max(log_sequence) from fnd_log_messages ; -- end 

E. Spool the output of the following query to an excel file which gives FND debug log: 

Run this script and replace start and end with the sequences you obtained from steps B and D. 

select module, message_text 

from fnd_log_messages 

where log_sequence between <start> and <end>;