Missing "kernel namespaces that are required for sandboxing" when rebuilding for a remote Rasberry Pi 3B

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Here is the whole output:

$ sudo nixos-rebuild --target-host admin@192.168.0.120 --sudo --flake .#pix boot
[sudo] password for emerald: 
warning: creating lock file "/home/emerald/Raspberry/flake.lock": 
• Added input 'nixpkgs':
    'github:nixos/nixpkgs/2fad6eac6077f03fe109c4d4eb171cf96791faa4?narHash=sha256-sKoIWfnijJ0%2B9e4wRvIgm/HgE27bzwQxcEmo2J/gNpI%3D' (2025-11-27)
building the system configuration...
error: this system does not support the kernel namespaces that are required for sandboxing; use '--no-sandbox' to disable sandboxing
Command 'nix --extra-experimental-features 'nix-command flakes' build --print-out-paths '.#nixosConfigurations."pix".config.system.build.toplevel' --no-link' returned non-zero exit status 1.

It’s not a lot. If there is some kind of argument that I can add to make the command print more info during execution, please tell me!

Posting the config that I am trying to build for the Raspberry Pi might be helpful too:

# flake.nix

{
  description = "Flake for Raspberry Pi 3B";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
  };

  outputs = { self, nixpkgs, ... } @ inputs: 
  {
    nixosConfigurations.pix = nixpkgs.lib.nixosSystem {
      system = "aarch64-linux";
      specialArgs = { inherit inputs; };
      modules = [
        ./configuration.nix
      ];
    };
  };
}

# configuration.nix

{ config, lib, pkgs, ... }:

{
  imports =
    [ # Include the results of the hardware scan.
      ./hardware-configuration.nix
    ];

  # Use the extlinux boot loader. (NixOS wants to enable GRUB by default)
  boot.loader.grub.enable = false;
  # Enables the generation of /boot/extlinux/extlinux.conf
  boot.loader.generic-extlinux-compatible.enable = true;

  nix.settings.experimental-features = [ "nix-command" "flakes" ];

  ...  # Some less relevant parts excluded

  # Define a user account.
  users.users.admin = {
    hashedPassword = "...";
    isNormalUser = true;
    extraGroups = [ "wheel" ]; 
  };

  ...  # Some less relevant parts excluded

  # Enable the OpenSSH daemon.
  services.openssh.enable = true;

  # Auto generated via "sudo nixos-generate-config"
  system.stateVersion = "26.05";
}

# hardware-configuration.nix

# Do not modify this file!  It was generated by ‘nixos-generate-config’
{ config, lib, pkgs, modulesPath, ... }:

{
  imports =
    [ (modulesPath + "/installer/scan/not-detected.nix")
    ];

  boot.initrd.availableKernelModules = [ "usbhid" ];
  boot.initrd.kernelModules = [ ];
  boot.kernelModules = [ ];
  boot.extraModulePackages = [ ];

  fileSystems."/" =
    { device = "/dev/disk/by-uuid/44444444-4444-4444-8888-888888888888";
      fsType = "ext4";
    };

  swapDevices = [ ];

  nixpkgs.hostPlatform = lib.mkDefault "aarch64-linux";
}

Hopefully we can figure something out from this :sweat_smile: