error: … while calling the 'derivationStrict' builtin at «nix-internal»/derivation-internal.nix:37:12: 36| 37| strict = derivationStrict drvAttrs; | ^ 38| … while evaluating derivation 'home-manager-generation' whose name attribute is located at «https://releases.nixos.org/nixos/unstable-small/nixos-26.11pre1078218.a251c42236bb/nixexprs.tar.xz?narHash=sha256-rrj0QhcnMUa9E7%2BD0NpF4FHpTgGsOXIDkh2ruzt641c%3D»/pkgs/stdenv/generic/make-derivation.nix:651:11 … while evaluating attribute 'buildCommand' of derivation 'home-manager-generation' at «https://releases.nixos.org/nixos/unstable-small/nixos-26.11pre1078218.a251c42236bb/nixexprs.tar.xz?narHash=sha256-rrj0QhcnMUa9E7%2BD0NpF4FHpTgGsOXIDkh2ruzt641c%3D»/pkgs/build-support/trivial-builders/default.nix:88:9: 87| inherit name; 88| buildCommand = lib.toFunction buildCommand finalAttrs; | ^ 89| passAsFile = defaultPassAsFile ++ (userAttrs.passAsFile or [ ]); … while evaluating the option `home.activation.installPackages.data': … while evaluating definitions from `/nix/store/xnygwnm7n6j5rnnwb4dcp0i2hlwq5amj-source/modules/home-environment.nix': (stack trace truncated; use '--show-trace' to show the full, detailed trace) error: Refusing to evaluate package 'tmate-unstable-2022-08-07' in /nix/store/fv9q2q4cbd2adhnjvlvczjaqzyyw1fdk-source/pkgs/by-name/tm/tmate/package.nix:55 because it is marked as insecure Known issues: - There are no upstream releases since 2019-11. - CVE-2018-19387 You can install it anyway by allowing this package, using the following methods: a) To temporarily allow all insecure packages, you can use an environment variable for a single invocation of the nix tools: $ export NIXPKGS_ALLOW_INSECURE=1 Note: When using `nix shell`, `nix build`, `nix develop`, etc with a flake, then pass `--impure` in order to allow use of environment variables. b) for `nixos-rebuild` you can add ‘tmate-unstable-2022-08-07’ to `nixpkgs.config.permittedInsecurePackages` in the configuration.nix, like so: { nixpkgs.config.permittedInsecurePackages = [ "tmate-unstable-2022-08-07" ]; } c) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add ‘tmate-unstable-2022-08-07’ to `permittedInsecurePackages` in ~/.config/nixpkgs/config.nix, like so: { permittedInsecurePackages = [ "tmate-unstable-2022-08-07" ]; }