I just downgraded from v6.5.4 to v5.6.16 to meet the requirements of a web app I am installing.
When I start the service (service elasticsearch start) it says OK, but when I check the status (service elasticsearch start), I get the following:
[root@ctl elasticsearch]# service elasticsearch status
● elasticsearch.service - Elasticsearch
Loaded: loaded (/usr/lib/systemd/system/elasticsearch.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Mon 2019-07-29 18:02:53 CDT; 11min ago
Docs: http://www.elastic.co
Process: 19878 ExecStart=/usr/share/elasticsearch/bin/elasticsearch -p {PID_DIR}/elasticsearch.pid --quiet -Edefault.path.logs={LOG_DIR} -Edefault.path.data={DATA_DIR} -Edefault.path.conf={CONF_DIR} (code=exited, status=1/FAILURE)
Process: 19876 ExecStartPre=/usr/share/elasticsearch/bin/elasticsearch-systemd-pre-exec (code=exited, status=0/SUCCESS)
Main PID: 19878 (code=exited, status=1/FAILURE)
Jul 29 18:02:53 ctl elasticsearch[19878]: at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:123)
Jul 29 18:02:53 ctl elasticsearch[19878]: at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:70)
Jul 29 18:02:53 ctl elasticsearch[19878]: at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:134)
Jul 29 18:02:53 ctl elasticsearch[19878]: at org.elasticsearch.cli.Command.main(Command.java:90)
Jul 29 18:02:53 ctl elasticsearch[19878]: at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:91)
Jul 29 18:02:53 ctl elasticsearch[19878]: at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:84)
Jul 29 18:02:53 ctl elasticsearch[19878]: Refer to the log for complete error details.
Jul 29 18:02:53 ctl systemd[1]: elasticsearch.service: main process exited, code=exited, status=1/FAILURE
Jul 29 18:02:53 ctl systemd[1]: Unit elasticsearch.service entered failed state.
Jul 29 18:02:53 ctl systemd[1]: elasticsearch.service failed