I just upgraded my instance to 0.18.0 using Ansible and I had to disable the option ‘Private instance’ directly on the database to get the lemmy docker up and running. I assume this is an intentional change, but should it really stop Lemmy from even running?
The check giving this error is pretty old, so it seems that you got it to work was not intentional: https://github.com/LemmyNet/lemmy/blame/63d3759c481ff2d7594d391ae86e881e2aeca56d/crates/api_common/src/utils.rs#L539
As far as I can see, 0.18 and its release candidates only added additional checks preventing such an instance to be set up in the first place.
I see, thank you for the insight. According to this comment, after an instance on 0.18.0 is running one can still set it to private with federation enabled, so it seems this check is only preventing the instance from starting in that state.