Help with: The ‘fileSystems’ option does not specify your root file system

      849|         || pred here (elemAt values 1) (head values) then
      850|           head values
         |           ^
      851|         else

   … while evaluating the attribute 'value'

     at /nix/store/8yr77rbqscv3xag45p5mxjbybsr3w3l5-nixos-23.11.1209.933d7dc15509/nixos/lib/modules.nix:807:9:

      806|     in warnDeprecation opt //
      807|       { value = builtins.addErrorContext "while evaluating the option `${showOption loc}':" value;
         |         ^
      808|         inherit (res.defsFinal') highestPrio;

   (stack trace truncated; use '--show-trace' to show the full trace)

   Failed assertions:
   - The ‘fileSystems’ option does not specify your root file system.

is there away to fix this error ?

As the error message tells you, you must declare a root filesystem in fileSystems.

how to do that it not allowing me

You’re going to nee to be more specific about what you’re trying to do to receive any help here.

Also, posting your current configuration would help us help you a ton.

# Edit this configuration file to define what should be installed on
# your system.  Help is available in the configuration.nix(5) man page
# and in the NixOS manual (accessible by running ‘nixos-help’).

{ config, pkgs, ... }:

  imports =
    [ # Include the results of the hardware scan.

  # Bootloader.
  boot.loader.grub.enable = true;
  boot.loader.grub.device = "/dev/sda";
  boot.loader.grub.useOSProber = true;

  networking.hostName = "nixos"; # Define your hostname.
  # networking.wireless.enable = true;  # Enables wireless support via wpa_supplicant.

  # Configure network proxy if necessary
  # networking.proxy.default = "http://user:password@proxy:port/";
  # networking.proxy.noProxy = ",localhost,internal.domain";

  # Enable networking
  networking.networkmanager.enable = true;

  # Set your time zone.
  time.timeZone = "America/New_York";

  # Select internationalisation properties.
  i18n.defaultLocale = "en_US.UTF-8";

  i18n.extraLocaleSettings = {
    LC_ADDRESS = "en_US.UTF-8";
    LC_MONETARY = "en_US.UTF-8";
    LC_NAME = "en_US.UTF-8";
    LC_NUMERIC = "en_US.UTF-8";
    LC_PAPER = "en_US.UTF-8";
    LC_TELEPHONE = "en_US.UTF-8";
    LC_TIME = "en_US.UTF-8";

  # Enable the X11 windowing system.
  services.xserver.enable = true;

  # Enable the GNOME Desktop Environment.
  services.xserver.displayManager.gdm.enable = true;
  services.xserver.desktopManager.gnome.enable = true;

  # Configure keymap in X11
  services.xserver = {
    layout = "us";
    xkbVariant = "";

  # Enable CUPS to print documents.
  services.printing.enable = true;

  # Enable sound with pipewire.
  sound.enable = true;
  hardware.pulseaudio.enable = false;
  security.rtkit.enable = true;
  services.pipewire = {
    enable = true;
    alsa.enable = true;
    alsa.support32Bit = true;
    pulse.enable = true;
    # If you want to use JACK applications, uncomment this
    #jack.enable = true;

    # use the example session manager (no others are packaged yet so this is enabled by default,
    # no need to redefine it in your config for now)
    #media-session.enable = true;

  # Enable touchpad support (enabled default in most desktopManager).
  # services.xserver.libinput.enable = true;

  # Define a user account. Don't forget to set a password with ‘passwd’.
  users.users.mark = {
    isNormalUser = true;
    description = "mark";
    extraGroups = [ "networkmanager" "wheel" ];
    packages = with pkgs; [
    #  thunderbird

  # Enable automatic login for the user.
  services.xserver.displayManager.autoLogin.enable = true;
  services.xserver.displayManager.autoLogin.user = "mark";

  # Workaround for GNOME autologin:"getty@tty1".enable = false;"autovt@tty1".enable = false;

  # Allow unfree packages
  nixpkgs.config.allowUnfree = true;

  # List packages installed in system profile. To search, run:
  # $ nix search wget
  environment.systemPackages = with pkgs; [
  #  vim # Do not forget to add an editor to edit configuration.nix! The Nano editor is also installed by default.
  #  wget

  # Some programs need SUID wrappers, can be configured further or are
  # started in user sessions.
  # = true;
  # programs.gnupg.agent = {
  #   enable = true;
  #   enableSSHSupport = true;
  # };

  # List services that you want to enable:

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

  # Open ports in the firewall.
  # networking.firewall.allowedTCPPorts = [ ... ];
  # networking.firewall.allowedUDPPorts = [ ... ];
  # Or disable the firewall altogether.
  # networking.firewall.enable = false;

  # This value determines the NixOS release from which the default
  # settings for stateful data, like file locations and database versions
  # on your system were taken. It‘s perfectly fine and recommended to leave
  # this value at the release version of the first install of this system.
  # Before changing this value read the documentation for this option
  # (e.g. man configuration.nix or on
  system.stateVersion = "23.11"; # Did you read the comment?


when i do nixos install it gives me that error

Please make use of formatting.

The error is self-explanatory. You have not declared fileSystems."/" in your configuration and I don’t see any fileSystems declarations either.

Are you installing NixOS with the graphical installer or did a manual install? Can you post your hardware-configuration.nix? The conflicting part of the config should be there.

# Do not modify this file!  It was generated by ‘nixos-generate-config’
# and may be overwritten by future invocations.  Please make changes
# to /etc/nixos/configuration.nix instead.
{ config, lib, pkgs, modulesPath, ... }:

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

  boot.initrd.availableKernelModules = [ "xhci_pci" "ahci" "ohci_pci" "ehci_pci" "usb_storage" "sd_mod" "sr_mod" "sdhci_pci" ];
  boot.initrd.kernelModules = [ ];
  boot.kernelModules = [ "kvm-amd" ];
  boot.extraModulePackages = [ ];

  fileSystems."/" =
    { device = "/dev/disk/by-uuid/d57180d7-e888-4689-8ad6-74b50ba598ae";
      fsType = "ext4";

  swapDevices =
    [ { device = "/dev/disk/by-uuid/c8acb6af-d6bf-49b6-ba3a-95177724ee87"; }

  # Enables DHCP on each ethernet and wireless interface. In case of scripted networking
  # (the default) this is the recommended approach. When using systemd-networkd it's
  # still possible to use this option, but it's recommended to use it in conjunction
  # with explicit per-interface declarations with `networking.interfaces.<interface>.useDHCP`.
  networking.useDHCP = lib.mkDefault true;
  # networking.interfaces.enp2s0.useDHCP = lib.mkDefault true;
  # networking.interfaces.wlp3s0.useDHCP = lib.mkDefault true;

  nixpkgs.hostPlatform = lib.mkDefault "x86_64-linux";
  hardware.cpu.amd.updateMicrocode = lib.mkDefault config.hardware.enableRedistributableFirmware;


Het mark, you can use tripple backticks ``` to begin and end code blocks in markdown formatting. The result looks like this

This is a codeblock

It has multiple lines

In this way people can better read your config files and have an easier time helping you! :slight_smile:

1 Like

hmm i have checked it over still flags end of the configuration file

error: syntax error, unexpected ‘;’
I have made no changes so far to it

It will probably say where is the problem. It will point to some place in your config, look above it and check if the syntax is correct. You can also try post here your config and the error, but don’t forget to use ``` in the beginning and in the end your pastes.

Please follow my lead from above and use backticks to demarcate code blocks. :slight_smile:

You can edit all your posts from above and transform them into code blocks. Then people can actually help you with syntax errors. Otherwise no one can really know what your file contents are.


I edited the blocks now, as the readability was atrocious.


I have this problem now.

I installed the system with nixos-anywhere, so it sort of figured the fileSystems bit out by itself, but can I somehow fetch this configuration?

I know I can write my own, but as the system has already booted, it should be possible to extract this declaration, no?