opensearch: securityadmin.sh: ERR: "CN=admin" is not an admin user

$ docker-compose exec opensearch01 plugins/opensearch-security/tools/securityadmin.sh -cd config -icl -nhnv -cacert config/ca.crt -cert config/admin.crt -
key config/admin.key
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** This tool will be deprecated in the next major release of OpenSearch **
** https://github.com/opensearch-project/security/issues/1755           **
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Security Admin v7
Will connect to localhost:9200 ... done
Connected as "CN=admin"
ERR: "CN=admin" is not an admin user
Seems you use a client certificate but this one is not registered as admin_dn
Make sure opensearch.yml on all nodes contains:
plugins.security.authcz.admin_dn:
  - ""CN=admin""