I put in a support case and got a response. Seems like this is a known issue with 9.4.0. I followed the resolution steps here and it seems to have worked for me. Had to do with the /etc/hosts file on the host machine. https://splunk.my.site.com/customer/s/article/After-upgrading-Splunk-from-v9-2-to-v9-4-the-Forwarder-Manager-Web-UI-is-unavailable ... View more

I am also seeing this issue. Any updates/solutions you've found? I've tried removing "restartSplunkWeb" from my app stanza declarations and made sure all the apps in the serverclass.conf exist in deplyoment-apps, but I'm still seeing that same error on forwarder management:   Forwarder management unavailable   There is an error in your serverclass.conf which is preventing deployment server from initializing. Please see your serverclass.conf.spec for more information. ... View more

Did you ever get this resolved? Seeing a similar issue. ... View more