Login screen broken

Possibly after upgrade to 12.7 and 12.8 from 12.6, the login screen stops working. The login screen shows a stack trace and the userid/passwd field below it. The userid/passwd field however are non-functional. Stack trace from the login screen and the corresponding Catalina.out file has been attached. Catalina.out data indicated null pointer exception for whatever reason.

The wiki was stable.The wiki is unusable now as a result.

Access to the broken wiki is possible on request.

Original problem reported on xwiki.org support forum.

https://forum.xwiki.org/t/unable-to-login-into-what-was-a-working-wiki/7504

ssh access to wiki VM available.