invalid stanza within default stanza [setup] - securegateway.conf

[SK3]

I am getting below error on HFs 

Invalid key in stanza [setup] in "/opt/splunk/etc/apps/splunk_secure_gateway/default/securegateway.conf", line 20: cluster_mode_enabled (value: false).

Can anybody tell us why?

[PickleRick]

Fisrtly, https://docs.splunk.com/Documentation/SecureGateway/3.5.15/Admin/ConfigureSecureGatewayConf

"In Splunk Secure Gateway version 3.4.25 and higher, Splunk Secure Gateway no longer reads from the securegateway.conf file. Configure Secure Gateway using the UI in Administration > Deployment configuration > Advanced settings"

Secondly, you should not need SSG on HFs.