When I see kibana logs, I found below error:
{"type":"log","@timestamp":"2020-12-24T06:25:54Z","tags":["info","plugins","security","authentication"],"pid":6,"message":"Authentication attempt failed: [security_exception] unable to authenticate user [es-upgrade-filebeat-beat-kb-user] for REST request [/_security/_authenticate], with { header={ WWW-Authenticate={ 0=\"Bearer realm=\\\"security\\\"\" & 1=\"ApiKey\" & 2=\"Basic realm=\\\"security\\\" charset=\\\"UTF-8\\\"\" } } }"}
{"type":"log","@timestamp":"2020-12-24T06:25:54Z","tags":["info","plugins","security","authentication"],"pid":6,"message":"Authentication attempt failed: [security_exception] unable to authenticate user [es-upgrade-auditbeat-beat-kb-user] for REST request [/_security/_authenticate], with { header={ WWW-Authenticate={ 0=\"Bearer realm=\\\"security\\\"\" & 1=\"ApiKey\" & 2=\"Basic realm=\\\"security\\\" charset=\\\"UTF-8\\\"\" } } }"}
{"type":"response","@timestamp":"2020-12-24T06:25:54Z","tags":["api"],"pid":6,"method":"get","statusCode":401,"req":{"url":"/api/status","method":"get","headers":{"host":"kibana-config-kb-http.es-upgrade.svc:5601","user-agent":"Go-http-client/1.1","accept":"application/json","content-type":"application/json","kbn-xsrf":"1","accept-encoding":"gzip"},"remoteAddress":"10.90.0.119","userAgent":"10.90.0.119"},"res":{"statusCode":401,"responseTime":46,"contentLength":9},"message":"GET /api/status 401 46ms - 9.0B"}
{"type":"response","@timestamp":"2020-12-24T06:25:54Z","tags":["api"],"pid":6,"method":"get","statusCode":401,"req":{"url":"/api/status","method":"get","headers":{"host":"kibana-config-kb-http.es-upgrade.svc:5601","user-agent":"Go-http-client/1.1","accept":"application/json","content-type":"application/json","kbn-xsrf":"1","accept-encoding":"gzip"},"remoteAddress":"10.90.0.40","userAgent":"10.90.0.40"},"res":{"statusCode":401,"responseTime":58,"contentLength":9},"message":"GET /api/status 401 58ms - 9.0B"}
{"type":"log","@timestamp":"2020-12-24T06:25:54Z","tags":["info","plugins","security","authentication"],"pid":6,"message":"Authentication attempt failed: [security_exception] unable to authenticate user [es-upgrade-packetbeat-beat-kb-user] for REST request [/_security/_authenticate], with { header={ WWW-Authenticate={ 0=\"Bearer realm=\\\"security\\\"\" & 1=\"ApiKey\" & 2=\"Basic realm=\\\"security\\\" charset=\\\"UTF-8\\\"\" } } }"}
{"type":"log","@timestamp":"2020-12-24T06:25:54Z","tags":["info","plugins","security","authentication"],"pid":6,"message":"Authentication attempt failed: [security_exception] unable to authenticate user [es-upgrade-auditbeat-beat-kb-user] for REST request [/_security/_authenticate], with { header={ WWW-Authenticate={ 0=\"Bearer realm=\\\"security\\\"\" & 1=\"ApiKey\" & 2=\"Basic realm=\\\"security\\\" charset=\\\"UTF-8\\\"\" } } }"}
{"type":"response","@timestamp":"2020-12-24T06:25:54Z","tags":["api"],"pid":6,"method":"get","statusCode":401,"req":{"url":"/api/status","method":"get","headers":{"host":"kibana-config-kb-http.es-upgrade.svc:5601","user-agent":"Go-http-client/1.1","accept":"application/json","content-type":"application/json","kbn-xsrf":"1","accept-encoding":"gzip"},"remoteAddress":"10.90.0.104","userAgent":"10.90.0.104"},"res":{"statusCode":401,"responseTime":42,"contentLength":9},"message":"GET /api/status 401 42ms - 9.0B"}
{"type":"response","@timestamp":"2020-12-24T06:25:54Z","tags":["api"],"pid":6,"method":"get","statusCode":401,"req":{"url":"/api/status","method":"get","headers":{"host":"kibana-config-kb-http.es-upgrade.svc:5601","user-agent":"Go-http-client/1.1","accept":"application/json","content-type":"application/json","kbn-xsrf":"1","accept-encoding":"gzip"},"remoteAddress":"10.90.0.134","userAgent":"10.90.0.134"},"res":{"statusCode":401,"responseTime":43,"contentLength":9},"message":"GET /api/status 401 43ms - 9.0B"}
{"type":"log","@timestamp":"2020-12-24T06:25:54Z","tags":["info","plugins","security","authentication"],"pid":6,"message":"Authentication attempt failed: [security_exception] unable to authenticate user [es-upgrade-auditbeat-beat-kb-user] for REST request [/_security/_authenticate], with { header={ WWW-Authenticate={ 0=\"Bearer realm=\\\"security\\\"\" & 1=\"ApiKey\" & 2=\"Basic realm=\\\"security\\\" charset=\\\"UTF-8\\\"\" } } }"}
{"type":"log","@timestamp":"2020-12-24T06:25:54Z","tags":["info","plugins","security","authentication"],"pid":6,"message":"Authentication attempt failed: [security_exception] unable to authenticate user [es-upgrade-filebeat-beat-kb-user] for REST request [/_security/_authenticate], with { header={ WWW-Authenticate={ 0=\"Bearer realm=\\\"security\\\"\" & 1=\"ApiKey\" & 2=\"Basic realm=\\\"security\\\" charset=\\\"UTF-8\\\"\" } } }"}