Thank you very much, diegodco31. Read the thread you metioned found that though iit is very simialr, the issue is different from our issue. In that thread the message is:
"User dcui@127.0.0.1 logged in as VMware-client/5.1.0
User dcui@127.0.0.1 logged out (login time: 25-08-2016 19:15:01, number of API invocations: 0, user agent: VMware-client/5.1.0) "
and every 5 minutes the message appears. And in our issue the message is:
User dcui@127.0.0.1 logged in as
User dcui@127.0.0.1 logged out (login time: Tuesday, 05 March, 2019, 17:43:01, number of API invocations: 0, user agent: )
and every minute the message appears, also there is no User agent in log message, which gives more suspious and strange.
In another comment sayingt that in hostd.log ( under /var/log) and search for this string " number of API invocations: 0, user agent: VMware-client/5.1.0" .
That line of log will tell who is invoking this . Most probably this can be "Vimsvc.ha-eventmgr" , which tells that HA agent is trying to get some status and then logging out.
Our issue has this message, but HA is not enabled in our enviroment.
Thank you again diegodco31! We appreciate your help and looking forward to further information.