Disable Registration

[sf0x]

Hi,
the First Server Run page claims that it is possible to disable signup to the server, but it does not describe how. I checked the configs and the documentation but found no explanation or config field that might do so.
Can you point out how I can disable registration of new users and limit the addition to manual admin changes?

Cheers,
sf0x

Edit: I set ACCOUNT_ALLOW_REGISTRATION to false, but it changes nothing, even though the code checks for it