Failed to connect to http://localhost:8086: Get http://localhost:8086/ping: dial tcp 127.0.0.1:8086: getsockopt: connection refused Please check your connection settings and ensure ‘influxd’ is running

After I run influxd -config ../../etc/influxdb/influxdb.conf, and then run `./influx`， an error occurred:
Failed to connect to http://localhost:8086: Get http://localhost:8086/ping: dial tcp 127.0.0.1:8086: getsockopt: connection refused Please check your connection settings and ensure ‘influxd’ is running

but if I change a new data dir， `influx` can run. Why does it happen?
like this

Start by reproducing `influxd -config ../../etc/influxdb/influxdb.conf` followed by `./influx`, then compare its behavior with a new data directory. Trace why the existing data directory leaves `http://localhost:8086/ping` unreachable; done means the cause and a verified resolution are documented.

Written by the indexing model from the issue text.