Error Occurred while accessing Siebel IP2015 AOM URL

When attempting to login to application, after entering the username and password, the following error occurs.

Encountered an error.

We are unable to process your request. This is most likely because you used the browser BACK or REFRESH button to get to this point.(SBL-UIF-00335)

The issue can be reproduced at will with the following steps:

1. Enter the Application URL.

2. Enter username and password.

3. Error is received.

It was working fine, till few days ago,

verified - cfg, webtmpl

Environment : Siebel IP 2015.

Your inputs are much appreciated.