Unable to launch Kibana after upgrade to 7.7.0

[skyluke.1987 (Luke)]

Hi all, yesterday I tried to upgrade my ELKS from 7.1 to 7.7. After the upgrade I am able to run the services and when I check its working and running. Just that I am not able to browse the site.

But there are following errors found:

Filebeat - ERROR instance/beat.go:932 Exiting: 1 error: invalid config: yaml: line 10: mapping values are not allowed in this context

ES:
[master-node] policy [filebeat-7.1.1] for index [filebeat-7.1.1-2020.05.27] on an error step due to a transitive error, moving back to the failed step [check-rollover-ready] for execution. retry attempt [110]
[2020-05-28T13:09:30,259][INFO ][o.e.x.i.IndexLifecycleRunner] [master-node] policy [heartbeat-7.1.1] for index [heartbeat-7.1.1-2020.05.28] on an error step due to a transitive error, moving back to the failed step [check-rollover-ready] for execution. retry attempt [39]

After I have deleted all the indices the error changed to: [o.e.x.s.a.AuthenticationService] [master-node] Authentication of [elastic] was terminated by realm [reserved] - failed to authenticate user [elastic]

Please advise should I remove all the old indices ?

[skyluke.1987 (Luke)]

Does anyone faced this issue after upgrade?

Besides that, I notice that my X-Pack does not work properly too, so I temporary disabled it. What do I need to do to fix it? I suspect that some other modules like Heartbeat-elastic (For Uptime) will need that in order to enable the Alerts system, is that true?