You cannot complete this task because one of the following events caused a loss of page data: A system failure has occurred "Front end is locked after 12.2 upgrade"

 If you have upgraded to Oracle E-Business Suite 12.2.10 Release Update Pack from Oracle E-Business Suite 12.2.6 Release Update Pack (or earlier) and after you apply the Release Update Pack (RUP) or perform an upgrade, your Oracle E-Business Suite system is locked down until the system administrator configures or acknowledges the recommended security configurations in the Secure Configuration Console to unlock the system for normal usage.

Error :

Use the below steps to unlock the front end through command line utility. 

Download and apply Below Patch : 

$ time adop phase=apply patches=31948857 hotpatch=yes

Unlock the Front end with the command line utiltiy :

Note : This command can be run from anywhere. FYI, I ran it from $ADMIN_SCRIPTS_HOME

$ java oracle.apps.fnd.security.AdminSecurityCfg -unlock DBC=<DBC file path>

 All output, errors and information can be found in the log file at $INST_TOP/logs/adminsecuritycfg_23_04_2021_19_16.log

Enter APPS username: apps

Enter APPS password:

*** Time [23/04/2021 19:16] ***

Running AdminSecurityCfg for UNLOCK mode

AdminSecurityCfg completed successfully.

I was able to open Front end after this fix.