Oops, you've found a dead link after upgrading JIRA to 8.13.6

[Pandiyan Muthuraman]

Recently have upgraded jira to latest LTS 8.13.6, after upgradation able to access console and perform login.

While trying to perform administration actions or access pages like "manage apps" "system" facing issue as "

Oops, you've found a dead link."

Tried following work around, still doesn't help

1. Cleared plugins cache /home/plugins
2. Double checked server.xml whether all settings are restored like proxy name, port. all are proper nothing reverted.

Still facing dead link while access manage apps, system JIRA pages.