Downgrade issues
NixOS und Nix support downgrades. That works mostly without issues, but some software complain when their state was created with a newer version. This page is to collect those softwares.
Syncthing
Refuses to start when downgraded.
[root@nixos:~]# journalctl -u syncthing.service ... WARNING: Failed to initialize config: config file version (36) is newer than supported version (35). If this is expected, use -allow-newer-config to override