I just updated my npins sources and now I’m getting this error:
error: ‘vivaldi’ has been removed due to lack of maintenance in nixpkgs
I see the last commit here nixpkgs/pkgs/applications/networking/browsers/vivaldi/default.nix at a59eb7800787c926045d51b70982ae285faa2346 · NixOS/nixpkgs · GitHub was 4 days ago?
Is there now a different way to install Vivaldi or how can I get it back? Vivaldi has been my goto browser for years and this is a real deal breaker.
Fortunately, it’s on flathub and that version works nicely.
See Flatpak - NixOS Wiki if you don’t know about flatpak (or for future readers)
and then
flatpak install flathub com.vivaldi.Vivaldi
Beware though that it saves its settings in .var/app/com.vivaldi.Vivaldi/ (in your home directory - I’ve lost my tilde key)
Thanks! Never used flatpak before. I guess I’ll have to try that until Vivaldi hopefully comes back to NixOS. I can’t really see why a change 4 days ago would target it as unmaintained and removed though.
There was a bit of a kerfuffle about that 
Looks like @wineee and one or two others have kindly stepped up to maintain it: vivaldi: re-init at 7.4.3684.43 by wineee · Pull Request #412571 · NixOS/nixpkgs · GitHub
Ah, awesome, so there’s hope it’s coming back!
Not “hope”, the PR was merged, so it is coming back.
Been following this nixpkgs PR status page (Nixpkgs PR #412571 ("vivaldi: re-init at 7.4.3684.43") progress) since yesterday. Not sure when the final nixpkgs stage will go green and the package actually be available in the unstable nixpkgs again though 
The version of Vivaldi in stable is working for me now 
Can confirm, nixpkgs-unstable vivaldi is back (at version 7.4.3684.43) and working for me as well. Thank you @max06 