"An unknown OPMN error has occurred""Error connecting to OPMN (is it running?): Connection refused: connect"

Stop all opmn and related process forcefully if does not stop from "stop SOA suite" script

Rename persistence to persistence.old in \SOA_HOME\OracleAS_1\j2ee\oc4j_soa\persistence

we will not be able to rename the folder if opmn or any related process is still running.

Use the following command to start SOA suite

opmnctl start
opmnctl startproc process-type=HTTP_Server
opmnctl startproc process-type=${oc4j_instance_name}
opmnctl startproc process-type=oc4j_soa