just got the error after yum upgrade 2018-11-23T11:13:35.493+0100 ERROR pipeline/output.go:100 Failed to connect to backoff(elasticsearch( https://xxxxxxxxxx:9200/var/log/apm-server )): 404 Not Found: {"error":{"root_cause":[{"type":"index_not_found_exception","reason":"no such index","resource.t…

Tx Sylvia, i have open a call on support and we find the solution. It was logfile enabled commented when line of path was not commented.

APM upgrade 6.5.0 to 6.5.1

Topic		Replies	Views
Trouble "reconnecting" APM after upgrade to 6.6.0 APM	5	760	March 1, 2019
APM Server has still not connected to Elasticsearch APM server	4	1630	June 18, 2019
APM server not connecting to ElasticSearch APM	3	1883	March 8, 2019
1. Apm server is not creating index in ElasticSearch APM server	6	1452	September 16, 2019
Failed to connect to backoff(elasticsearch(http://es01:9200)): Connection marked as failed because the onConnect callback failed: resource 'apm-7.5.2-error' exists, but it is not an alias APM	5	7488	June 30, 2020