With merge of PR #8390 we updated lighttpd to the latest version 1.4.64 which removed support for the deprecated option server.set-v6only.
This option’s default was true in upstream since our update to version 1.4.46 but we disabled it with a patch to prevent breaking existing lighttpd installations.
The new update doesn’t allow to disable it anymore, meaning we break existing installs which used server.set-v6only.
If you’re affected, please change your lighttpd configuration to use different sockets for ipv4 and ipv6 connections.