Apparently they're on 1.34, on the latest-but-one nixos stable, and can't upgrade to latest nixos stable because of an unrelated openldap issue. That's not on you.
I talked to the room admin and apparently when they create a new room (latest synapse, latest element) it gets set to v9 by default and they can't do anything about it.
It's NixOS... could they pull just that package from the release-21.05 channel? E.g.,
let
newerPkgs = import (builtins.fetchGit {
name = "release-21.05-pkgs";
url = "https://github.com/NixOS/nixpkgs/";
ref = "refs/heads/release-21.05";
rev = "8d6407e5a442e5e2fc50c3ca36411b6995afbc17";
}) {};
in
I may have the syntax slightly wrong, but something like that.
Edit: Ah, except Synapse is a service, so things get a little more complicated. https://nixos.wiki/wiki/FAQ/Pinning_Nixpkgs has some pointers.
Synapse 1.42 and 1.43 both support Room Version 9, and should be available pretty much everywhere. Do you know what distro your homeserver admin is running? Looks like FreeBSD and Ubuntu might be lagging, but Arch, Debian, Docker, Fedora, openSUSE, etc. all look fine. If you're on Ubuntu, we maintain our own repository with debs for the currently supported Debian and Ubuntu releases: https://matrix-org.github.io/synapse/v1.43/setup/installatio...