Librewolf throwing rebuild errors about backuping files

I recently wanted to change my librewolf setup to be incorperated into my nixos config. everything seems to work, except that i always get error messages like:

activating the configuration...
setting up /etc...
reloading user units for noof...
restarting sysinit-reactivation.target
the following new units were started: NetworkManager-dispatcher.service, searx.service
warning: the following units failed: home-manager-noof.service
× home-manager-noof.service - Home Manager environment for noof
     Loaded: loaded (/etc/systemd/system/home-manager-noof.service; enabled; preset: ignored)
     Active: failed (Result: exit-code) since Sun 2025-06-15 10:45:08 CEST; 267ms ago
 Invocation: b458b022f4204b4a8f98967faddd4a2d
    Process: 607430 ExecStart=/nix/store/8axxcgpnr78xkhy46yy2dxf5nwjwswv8-hm-setup-env /nix/store/35gcnc3izi4zkkjvv9h49s550ikxgnpr-home-manager-generation (code=exited, status=1/FAILURE)
   Main PID: 607430 (code=exited, status=1/FAILURE)
         IP: 0B in, 0B out
         IO: 0B read, 0B written
   Mem peak: 5M
        CPU: 240ms

Jun 15 10:45:08 cesium hm-activate-noof[607588]: - Move or remove the files below and try again.
Jun 15 10:45:08 cesium hm-activate-noof[607588]: - In standalone mode, use 'home-manager switch -b backup' to back up
Jun 15 10:45:08 cesium hm-activate-noof[607588]:   files automatically.
Jun 15 10:45:08 cesium hm-activate-noof[607588]: - When used as a NixOS or nix-darwin module, set
Jun 15 10:45:08 cesium hm-activate-noof[607588]:     'home-manager.backupFileExtension'
Jun 15 10:45:08 cesium hm-activate-noof[607588]:   to, for example, 'backup' and rebuild.
Jun 15 10:45:08 cesium hm-activate-noof[607588]: Existing file '/home/noof/.librewolf/main/search.json.mozlz4.backup' would be clobbered by backing up '/home/noof/.librewolf/main/search.json.mozlz4'
Jun 15 10:45:08 cesium systemd[1]: home-manager-noof.service: Main process exited, code=exited, status=1/FAILURE
Jun 15 10:45:08 cesium systemd[1]: home-manager-noof.service: Failed with result 'exit-code'.
Jun 15 10:45:08 cesium systemd[1]: Failed to start Home Manager environment for noof.

has anyone any idea what this means and why it happens?

here is my librewolf config:

{ pkgs, ... }:
let
  ublock-settings = {
    "uBlock0@raymondhill.net".settings = {
      selectedFilterLists = [
        "ublock-filters"
        "ublock-badware"
        "ublock-privacy"
        "ublock-ubreak"
        "ublock-quick-fixes"
      ];
    };
  };
in
{
  programs.librewolf = {
    enable = true;
    languagePacks = [
      "de"
      "en-US"
    ];
    policies = {
      DisableTelemetry = true;
      DisableFirefoxStudies = true;
      #BlockAboutConfig = true;
    };
    profiles = {
      main = {
        #extensions = {
        #packages = with pkgs.nur.repos.rycee.firefox-addons; [
        #ublock-origin
        #];
        #settings = ublock-settings; # use ublock-settings // other_settings to concat
        #force = true;
        #};
        isDefault = true; # selected by default
        name = "main";
        search = {
          default = "startpage";
          engines = {
            startpage = {
              name = "Startpage";
              urls = [
                {
                  template = "https://startpage.com/";
                  params = [
                    {
                      name = "q";
                      value = "{searchTerms}";
                    }
                  ];
                }
              ];
            };
          };
        };
      };
    };
    settings = {
      "accessability.blockautorefresh" = true;
      "accessability.browsewithcaret" = false;
      "accessability.browsewithcaret_shortcut.enabled" = false;
      "apz.enable_double_tap_zooming" = false;
      "browser.backup.enabled" = false;
      "browser.contentblocking.category" = "strict";
      "cookiebanners.service.mode.privateBrowsing" = 2;
      "cookiebanners.service.mode" = 2;
      "privacy.donottrackheader.enabled" = true;
      "privacy.fingerprintingProtection" = true;
      "privacy.resistFingerprinting" = true;
      "privacy.trackingprotection.emailtracking.enabled" = true;
      "privacy.trackingprotection.enabled" = true;
      "privacy.trackingprotection.fingerprinting.enabled" = true;
      "privacy.trackingprotection.socialtracking.enabled" = true;
      "browser.newtabpage.enabled" = false;
      "browser.tabs.allow_transparent_browser" = true;
      "sidebar.verticalTabs" = true;
    };
  };
}

thanks already.

I got the same issue. Thought it was bc I configured profiles.<name>.search.engines around the same time I got the error. Did your search engine config work before?

i have an absolutely massive config for librewolf that i still have yet to FINISH, since i made it before i started using home-manager, or rather nix-maid, cos some of the preferences are ignored by mozilla policies, as well as some values are outdated, blah blah blah, thats besides the point… anyway, it works quite well, perhaps you’ll find something that you like? once again, this is WITHOUT the home-manager, so it looks insane, like this:

  environment.etc."firefox/policies/policies.json".target = "librewolf/policies/policies.json"; # use if prefs.js and/or policies.json dont apply
  programs.firefox = {
    enable = true;
    package = pkgs.librewolf; 
    # nativeMessagingHosts.ff2mpv = true; # 'pkgs.ff2mpv-rust'? -- https://addons.mozilla.org/en-US/firefox/addon/ff2mpv/
    languagePacks = [ # doesnt work?
      "nl"
      "en-GB"
    ];
    preferencesStatus = "locked"; # "programs.firefox.autoConfig"?
    policies = { # JSON values -- about:policies#documentation -- https://mozilla.github.io/policy-templates
      # ...
      RequestedLocales = "nl,en-GB"; # doesnt work?
      AppAutoUpdate = false;
      BackgroundAppUpdate = false;
      CaptivePortal = false;
      DisableAppUpdate = true;
      DisableTelemetry = true;
      DisableFirefoxStudies = true;
      DisableFirefoxAccounts = true;
      DisableFirefoxScreenshots = true;
      DisableFeedbackCommands = true;
      DisableFormHistory = true;
      DisableSetDesktopBackground = true;
      DisablePocket = true;
      DontCheckDefaultBrowser = true;
      GoToIntranetSiteForSingleWordEntryInAddressBar = false;
      PrintingEnabled = false;
      SearchSuggestEnabled = false;
      TranslateEnabled = false;
      OverrideFirstRunPage = ""; # "startup.homepage_welcome_url"
      OverridePostUpdatePage = ""; # "startup.homepage_override_url"
      NoDefaultBookmarks = true;
      DisplayBookmarksToolbar = "newtab";
      DisplayMenuBar = "default-off";
      SkipTermsOfUse = true;
      ShowHomeButton = false;
      SearchBar = "unified";
      HardwareAcceleration = true;
      UseSystemPrintDialog = true;
      PasswordManagerEnabled = false;
      AutofillAddressEnabled = false;
      AutofillCreditCardEnabled = false;
      OfferToSaveLogins = false;
      PromptForDownloadLocation = true;
      # StartDownloadsInTempDirectory = true; # faster -- RAM?
      EncryptedMediaExtensions = {
        Enabled = false; # DRM -- widevine
        Locked = true;
      };
      FirefoxHome = {
        Search = false;
        TopSites = false;
        SponsoredTopSites = false;
        Highlights = false;
        Pocket = false;
        SponsoredPocket = false;
        Snippets = false;
        Locked = true;
      };
      FirefoxSuggest = {
        WebSuggestions = false;
        SponsoredSuggestions = false;
        ImproveSuggest = false;
        Locked = true;
      };
      UserMessaging = {
        ExtensionRecommendations = false;
        FeatureRecommendations = false;
        MoreFromMozilla = false;
        SkipOnboarding = true;
        UrlbarInterventions = false;
        WhatsNew = false;
        Locked = true;
      };
      PopupBlocking = {
        Default = false;
        Locked = true;
      };
      DisableBuiltinPDFViewer = true; # MIME / XDG?
      Handlers = {
        mimeTypes."application/pdf".action = "saveToDisk";
      };
      PDFjs = {
        Enabled = false;
        EnablePermissions = false;
      };
      Permissions = {
        Camera = {
          BlockNewRequests = true;
          Locked = true;
        };
        Microphone = {
          BlockNewRequests = true;
          Locked = true;
        };
        Location = {
          BlockNewRequests = true;
          Locked = true;
        };
        Notifications = {
          BlockNewRequests = true;
          Locked = true;
        };
        Autoplay = {
          Default = "block-audio"; # "allow-audio-video", "block-audio", "block-audio-video"
          Locked = true;
        };
      };
      PictureInPicture = {
        Enabled = false;
        Locked = true;
      };
      SanitizeOnShutdown = {
        Cache = true;
        Cookies = false;
        Downloads = true;
        FormData = true;
        History = false;
        Sessions = false;
        SiteSettings = false;
        OfflineApps = true;
        Locked = true;
      };
      SearchEngines = {
        PreventInstalls = true;
        Add = [
          {
            Name = "GOOD"; 
            URLTemplate = "https://good-search.org/search?q={searchTerms}";
            Method = "GET"; # "POST"
            IconURL = "https://good-search.org/favicon.ico";
          }
          { Name = "Ecosia";
            URLTemplate = "https://www.ecosia.org/search?q={searchTerms}";
            Method = "GET"; # "POST"
            IconURL = "https://www.ecosia.org/favicon.ico";
          }
          {
            Name = "SearXNG (NL)";
            URLTemplate = "https://search.rhscz.eu/search?q={searchTerms}";
            Method = "GET"; # "POST"
            IconURL = "https://search.rhscz.eu/favicon.ico";
          }
          {
            Name = "SearXNG (DE)";
            URLTemplate = "https://search.citw.lgbt/search?q={searchTerms}";
            Method = "GET"; # "POST"
            IconURL = "https://search.citw.lgbt/favicon.ico";
          }
          {
            Name = "Startpage";
            URLTemplate = "https://www.startpage.com/search?q={searchTerms}";
            Method = "GET"; # "POST"
            IconURL = "https://www.startpage.com/favicon.ico";
          }
          {
            Name = "MetaGer";
            URLTemplate = "https://metager.org/search?q={searchTerms}";
            Method = "GET"; # "POST"
            IconURL = "https://metager.org/favicon.ico";
          }
          {
            Name = "Searchix";
            URLTemplate = "https://searchix.ovh/?query={searchTerms}";
            Method = "GET"; # "POST"
            IconURL = "https://searchix.ovh/favicon.ico";
          }
          {
            Name = "NixOS Search";
            URLTemplate = "https://search.nixos.org/packages?channel=unstable&query={searchTerms}";
            Method = "GET"; # "POST"
            IconURL = "https://search.nixos.org/favicon.png";
          }
          # ...
          # ...
          # ...
        ];
        Remove = [
          # ...
          "Google"
          "Bing"
          "DuckDuckGo"
          "Yahoo"
          "Yandex"
          "eBay"
          "Wikipedia"
          # ...
        ];
        Default = "Ecosia";
      };
      # ...
      Preferences = { # https://searchfox.org/mozilla-central/source/ -- https://mozilla.github.io/policy-templates/#preferences -- https://ffprofile.com/
        # ...
        "accessibility.force_disabled" = 1;
        "app.normandy.api_url" = "";
        "app.normandy.enabled" = false;
        "app.shield.optoutstudies.enabled" = false;
        "app.update.auto" = false;
        "apz.autoscroll.enabled" = false; # MOUSE3 scrolling -- "middlemouse.*"?
        "apz.gtk.kinetic_scroll.enabled" = false;
        "apz.overscroll.enabled" = false;
        "beacon.enabled" = false;
        "breakpad.reportURL" = "";
        "browser.aboutConfig.showWarning" = false;
        "browser.backspace_action" = 0; # OG previous page key
        "browser.cache.offline.enable" = false;
        "browser.compactmode.show" = true;
        "browser.crashReports.unsubmittedCheck.autoSubmit" = false;
        "browser.crashReports.unsubmittedCheck.autoSubmit2" = false;
        "browser.crashReports.unsubmittedCheck.enabled" = false;
        "browser.disableResetPrompt" = true;
        "browser.display.use_document_fonts" = 0;
        "browser.download.alwaysOpenPanel" = false;
        "browser.fixup.alternate.enabled" = false; # "www" & ".com"
        "browser.formfill.enable" = false;
        "browser.fullscreen.animate" = false;
        "browser.fullscreen.animateUp" = 0;
        "browser.ml.chat.enabled" = false; # piss off
        "browser.newtab.preload" = false;
        "browser.newtabpage.activity-stream.feeds.section.topstories" = false;
        "browser.newtabpage.activity-stream.feeds.snippets" = false;
        "browser.newtabpage.activity-stream.improvesearch.handoffToAwesomebar" = false;
        "browser.newtabpage.activity-stream.section.highlights.includeBookmarks" = false;
        "browser.newtabpage.activity-stream.section.highlights.includeDownloads" = false;
        "browser.newtabpage.activity-stream.section.highlights.includePocket" = false;
        "browser.newtabpage.activity-stream.section.highlights.includeVisited" = false;
        "browser.newtabpage.activity-stream.showSponsored" = false;
        "browser.newtabpage.activity-stream.showSponsoredTopSites" = false;
        "browser.newtabpage.activity-stream.system.showSponsored" = false;
        "browser.newtabpage.enabled" = false;
        "browser.newtabpage.enhanced" = false;
        "browser.newtabpage.introShown" = true;
        "browser.pagethumbnails.capturing_disabled" = true;
        "browser.preferences.defaultPerformanceSettings.enabled" = false;
        "browser.safebrowsing.appRepURL" = "";
        "browser.safebrowsing.blockedURIs.enabled" = false;
        "browser.safebrowsing.downloads.enabled" = false;
        "browser.safebrowsing.downloads.remote.enabled" = false;
        "browser.safebrowsing.downloads.remote.url" = "";
        "browser.safebrowsing.enabled" = false;
        "browser.safebrowsing.malware.enabled" = false;
        "browser.safebrowsing.phishing.enabled" = false;
        # "browser.search.openintab" = true;
        "browser.search.suggest.enabled" = false;
        "browser.search.suggest.enabled.private" = false;
        "browser.selfsupport.url" = "";
        "browser.send_pings" = false;
        "browser.sessionstore.interval" = 300000; # 5 minutes
        "browser.sessionstore.privacy_level" = 2; # extra=0, http=1, never=2
        "browser.sessionstore.resume_from_crash" = false;
        "browser.shell.checkDefaultBrowser" = false;
        "browser.shell.shortcutFavicons" = false;
        "browser.startup.blankWindow" = true;
        "browser.startup.homepage" = "about:blank";
        "browser.startup.homepage_override.mstone" = "ignore";
        "browser.startup.page" = 3; # about:blank=0, about:home=1, last=2, restore=3
        "browser.tabs.animate" = false;
        "browser.tabs.closeWindowWithLastTab" = false;
        "browser.tabs.crashReporting.sendReport" = false;
        "browser.tabs.hoverPreview.enabled" = false;
        "browser.tabs.loadInBackground" = false; 
        "browser.tabs.loadDivertedInBackground" = true;
        "browser.tabs.tabClipWidth" = 1280;
        "browser.tabs.tabmanager.enabled" = false;
        "browser.tabs.tabMinWidth" = 69;
        "browser.tabs.warnOnClose" = false;
        "browser.topsites.contile.enabled" = false;
        "browser.translations.automaticallyPopup" = false;
        "browser.translations.enable" = false;
        "browser.uidensity" = 1;
        "browser.urlbar.groupLabels.enabled" = false;
        # "browser.urlbar.openintab" = true;
        "browser.urlbar.quicksuggest.enabled" = false;
        "browser.urlbar.showSearchSuggestionsFirst" = false;
        "browser.urlbar.speculativeConnect.enabled" = false;
        "browser.urlbar.shortcuts.bookmarks" = false;
        "browser.urlbar.shortcuts.history" = false;
        "browser.urlbar.shortcuts.tabs" = false;
        "browser.urlbar.suggest.addons" = false;
        # "browser.urlbar.suggest.bookmark" = false;
        "browser.urlbar.suggest.calculator" = false;
        "browser.urlbar.suggest.clipboard" = false;
        "browser.urlbar.suggest.engines" = false;
        "browser.urlbar.suggest.fakespot" = false;
        "browser.urlbar.suggest.mdn" = false;
        "browser.urlbar.suggest.pocket" = false;
        "browser.urlbar.suggest.quickactions" = false;
        "browser.urlbar.suggest.quicksuggest.nonsponsored" = false;
        "browser.urlbar.suggest.quicksuggest.sponsored" = false;
        # "browser.urlbar.suggest.searches" = false;
        "browser.urlbar.suggest.topsites" = false;
        "browser.urlbar.suggest.trending" = false;
        "browser.urlbar.suggest.weather" = false;
        "browser.urlbar.suggest.yelp" = false;
        "browser.urlbar.trimURLs" = false;
        "browser.warnOnQuit" = false; 
        "cookiebanners.bannerClicking.enabled" = false; # UBLOCK!
        "cookiebanners.bannerClicking.testing" = false; # UBLOCK!
        "cookiebanners.cookieInjector.enabled" = false; # UBLOCK!
        "cookiebanners.service.enableGlobalRules" = false; # UBLOCK!
        "cookiebanners.service.mode" = 0; # UBLOCK! -- off=0, reject=1, accept=2
        "cookiebanners.service.mode.privateBrowsing" = 0; # UBLOCK! -- off=0, reject=1, accept=2
        "cookiebanners.ui.desktop.enabled" = false; # UBLOCK!
        "datareporting.healthreport.service.enabled" = false;
        "datareporting.healthreport.uploadEnabled" = false;
        "datareporting.policy.dataSubmissionEnabled" = false;
        "device.sensors.ambientLight.enabled" = false;
        "device.sensors.enabled" = false;
        "device.sensors.motion.enabled" = false;
        "device.sensors.orientation.enabled" = false;
        "device.sensors.proximity.enabled" = false;
        "dom.battery.enabled" = false;
        "dom.event.clipboardevents.enabled" = false;
        "dom.private-attribution.submission.enabled" = false;
        "dom.ipc.processCount" = 8; # CPU threads
        # "dom.ipc.processCount.webisolated" = 8; # CPU threads
        "dom.security.https_only_mode" = true;
        "dom.security.https_only_mode_ever_enabled" = true;
        "dom.serviceWorkers.enabled" = false;
        # "dom.webaudio.enabled" = false; # audio playback
        "experiments.activeExperiment" = false;
        "experiments.enabled" = false; 
        "experiments.manifest.uri" = "";
        "experiments.supported" = false;
        "extensions.experiments.enabled" = false;
        "extensions.getAddons.cache.enabled" = false;
        "extensions.getAddons.showPane" = false;
        "extensions.greasemonkey.stats.optedin" = false;
        "extensions.greasemonkey.stats.url" = "";
        # "extensions.langpacks.signatures.required" = false; # ublock deleting itself?
        "extensions.pocket.enabled" = false; 
        "extensions.shield-recipe-client.api_url" = "";
        "extensions.shield-recipe-client.enabled" = false;
        "extensions.webservice.discoverURL" = "";
        "findbar.highlightAll" = true;
        # "full-screen-api.enabled" = false;
        "full-screen-api.transition.timeout" = 0; 
        "full-screen-api.warning.delay" = 0; 
        "full-screen-api.warning.timeout" = 0; 
        "general.smoothScroll" = false;
        "general.smoothScroll.lines" = false;
        "general.smoothScroll.mouseWheel" = false;
        "general.smoothScroll.other" = false;
        "general.smoothScroll.pages" = false;
        "general.smoothScroll.pixels" = false;
        "geo.enabled" = false;
        "identity.fxaccounts.enabled" = false;
        "image.animation_mode" = "once"; # "none"
        "image.mem.decode_bytes_at_a_time" = 131072;
        "image.mem.surfacecache.max_size_kb" = 420000;
        "intl.accept_languages" = "nl,en-GB"; # doesnt work?
        "intl.locale.requested" = "nl,en-GB"; # doesnt work?
        "keyword.enabled" = false; # URL?
        "layers.acceleration.disabled" = false; # hardware acceleration video artifacts?
        "layers.acceleration.force-enabled" = false; # hardware acceleration video artifacts?
        "layout.css.always_underline_links" = true;
        "layout.css.animation-composition.enabled" = false;
        "layout.css.font-visibility.private" = 1;
        "layout.css.font-visibility.resistFingerprinting" = 1;
        "layout.css.font-visibility.standard" = 1;
        "layout.css.font-visibility.trackingprotection" = 1;
        "layout.css.prefers-color-scheme.content-override" = 0; # dark theme
        "layout.css.prefers-reduced-transparency.enabled" = true;
        "layout.css.prefixes.animations" = false;
        "layout.css.scrollbar-width-thin.disabled" = true;
        "layout.css.system-ui.enabled" = false;
        "layout.spellcheckDefault" = 0;
        "layout.testing.overlay-scrollbars.always-visible" = true;
        "media.autoplay.default" = 0;
        "media.autoplay.enabled" = true;
        "media.autoplay.blocking_policy" = 2; # sticky=0, transient=1, click-to-play=2
        "media.cubeb.backend" = "alsa"; # "pulse-rust", "oss", "sndio", "alsa", "jack", "pulse"
        "media.eme.enabled" = false; # widevine content decryption module -- DRM HTML5
        "media.getusermedia.aec_enabled" = false;
        "media.getusermedia.agc_enabled" = false;
        "media.getusermedia.noise_enabled" = false;
        "media.getusermedia.hpf_enabled" = false;
        "media.gmp-widevinecdm.enabled" = false;
        # "media.hardware-video-decoding.enabled" = true; # hardware acceleration video artifacts?
        # "media.hardware-video-decoding.force-enabled" = true; # hardware acceleration video artifacts?
        "media.hardwaremediakeys.enabled" = false;
        "media.navigator.enabled" = false;
        "media.navigator.mediadatadecoder_vpx_enabled" = false; # hardware acceleration video artifacts?
        "media.peerconnection.enabled" = false;
        "media.videocontrols.picture-in-picture.video-toggle.enabled" = false;
        "media.video_stats.enabled" = false;
        "media.volume_scale" = 1.0; # default=0 -- ALSA / pulseaudio / pipewire volume random "jumping"?
        # "middlemouse.contentLoadURL" = false;
        # "middlemouse.openNewWindow" = false;
        # "middlemouse.paste" = false;
        # "mousewheel.min_line_scroll_amount" = 10; # default=1
        "network.allow-experiments" = false; 
        "network.captive-portal-service.enabled" = false;
        "network.cookie.cookieBehavior" = 1; # no=0, 3p=1, all=2, unvisited=3, jar=4
        "network.dns.disablePrefetch" = true;
        "network.dns.disablePrefetchFromHTTPS" = true;
        "network.http.rcwn.enabled" = false;
        "network.http.referer.spoofSource" = true;
        "network.http.speculative-parallel-limit" = 0;
        "network.IDN_show_punycode" = true;
        "network.predictor.enable-prefetch" = false;
        "network.predictor.enabled" = false;
        "network.prefetch-next" = false;
        "network.protocol-handler.expose.magnet" = false;
        "network.protocol-handler.expose.torrent" = false;
        "network.standard-url.escape-utf8" = false; # https://en.wikipedia.org/wiki/Percent-encoding
        "network.trr.mode" = 5; # default=0 (off), race=1, first=2, only=3, shadow=4, off=5 (choice)
        "pageThumbs.enabled" = false;
        "pdfjs.enableScripting" = false;
        "privacy.clearOnShutdown.downloads" = true;
        "privacy.clearOnShutdown.history" = false;
        "privacy.donottrackheader.enabled" = true;
        "privacy.donottrackheader.value" = 1;
        "privacy.fingerprintingProtection" = true;
        "privacy.globalprivacycontrol.enabled" = true;
        "privacy.globalprivacycontrol.functionality.enabled" = true;
        "privacy.query_stripping" = true;
        "privacy.resistFingerprinting" = true;
        # "privacy.resistFingerprinting.letterboxing" = true; # window content size
        "privacy.trackingprotection.cryptomining.enabled" = true;
        "privacy.trackingprotection.emailtracking.enabled" = true;
        "privacy.trackingprotection.enabled" = true;
        "privacy.trackingprotection.fingerprinting.enabled" = true;
        "privacy.trackingprotection.pbmode.enabled" = true;
        "privacy.trackingprotection.socialtracking.enabled" = true;
        "privacy.userContext.about_newtab_segregation.enabled" = true;
        "privacy.userContext.enabled" = false;
        "privacy.userContext.ui.enabled" = false;
        "security.ssl.disable_session_identifiers" = true;
        "services.sync.prefs.sync.browser.newtabpage.activity-stream.showSponsoredTopSite" = false;
        "services.sync.prefs.sync.browser.urlbar.suggest.engines" = false;
        "services.sync.prefs.sync.browser.urlbar.suggest.topsites" = false;
        "sidebar.animation.enabled" = false;
        "signon.autofillForms" = false;
        "toolkit.cosmeticAnimations.enabled" = false;
        "toolkit.scrollbox.smoothScroll" = false;
        "toolkit.telemetry.archive.enabled" = false;
        "toolkit.telemetry.bhrPing.enabled" = false;
        "toolkit.telemetry.cachedClientID" = "";
        "toolkit.telemetry.enabled" = false;
        "toolkit.telemetry.firstShutdownPing.enabled" = false;
        "toolkit.telemetry.hybridContent.enabled" = false;
        "toolkit.telemetry.newProfilePing.enabled" = false;
        "toolkit.telemetry.prompted" = 2;
        "toolkit.telemetry.rejected" = true;
        "toolkit.telemetry.reportingpolicy.firstRun" = false;
        "toolkit.telemetry.server" = "";
        "toolkit.telemetry.shutdownPingSender.enabled" = false;
        "toolkit.telemetry.unified" = false;
        "toolkit.telemetry.unifiedIsOptIn" = false;
        "toolkit.telemetry.updatePing.enabled" = false;
        "ui.prefersReducedMotion" = 1; # animations
        "ui.SpellCheckerUnderlineStyle" = 0;
        "webgl.disabled" = true; # 3D graphics
        # "webgl.force-enabled" = true; # 3D graphics
        # "webgl.msaa-force" = true; # antialising
        "webgl.renderer-string-override" = " ";
        "webgl.vendor-string-override" = " ";
        "widget.non-native-theme.scrollbar.style" = 4; # macos=1, gtk=2, android=3, win10=4, win11=5
        "widget.use-xdg-desktop-portal.file-picker" = 1; # "xdg.portal.xdgOpenUsePortal"?
        # ...
        # ...
        # ...
      };
      ExtensionUpdate = true;
      ExtensionSettings = { # https://mozilla.github.io/policy-templates/#extensionsettings
        # ...
        "*" = {
          installation_mode = "blocked"; # GUID
          blocked_install_message = "NOPE";
          # temporarily_allow_weak_signatures = true; # unsigned addons?
        };
        "uBlock0@raymondhill.net" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/ublock-origin/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "navbar";
        };
        "sponsorBlocker@ajay.app" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/sponsorblock/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "menupanel";
        };
        "jid1-MnnxcxisBPnSXQ@jetpack" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/privacy-badger17/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "menupanel";
        };
        "jid1-BoFifL9Vbdl2zQ@jetpack" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/decentraleyes/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "menupanel";
        };
        "jid0-3GUEt1r69sQNSrca5p8kx9Ezc3U@jetpack" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/terms-of-service-didnt-read/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "navbar";
        };
        "{b43b974b-1d3a-4232-b226-eaa2ac6ebb69}" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/random_user_agent/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "navbar";
        };
        "{73a6fe31-595d-460b-a920-fcc0f8843232}" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/noscript/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "navbar";
        };
        "CanvasBlocker@kkapsner.de" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/canvasblocker/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "navbar";
        };
        "uMatrix@raymondhill.net" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/umatrix/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "navbar";
        };
        "{74145f27-f039-47ce-a470-a662b129930a}" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/clearurls/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "menupanel";
        };
        "addon@darkreader.org" = {
          install_url = "https://addons.mozilla.org/firefox/downloads/latest/darkreader/latest.xpi";
          installation_mode = "normal_installed";
          updates_disabled = false;
          private_browsing = true;
          default_area = "navbar";
        };
        # ...
        # ...
        # ...
      };
      # ...
      "3rdparty".Extensions = { # WebExtensions declarative preferences -- https://mozilla.github.io/policy-templates/#3rdparty
        # ...
        "uBlock0@raymondhill.net".adminSettings = {
          userSettings = { # 'rec'? -- "~/.librewolf/abcdefgh.default/extensions/uBlock0@raymondhill.net.xpi/settings.html"
            uiTheme = "dark";
            uiAccentCustom = true;
            uiAccentCustom0 = "#ff00ff";
            cloudStorageEnabled = lib.mkForce false; 
            # noCosmeticFiltering = true; # "no-cosmetic-filtering"
            # noLargeMedia = true; # "no-large-media"
            # noRemoteFonts = true; # "no-remote-fonts"
            # noScripting = true; # "no-scripting"
            /*
            importedLists = [
              # ...
              "https://filters.adtidy.org/extension/ublock/filters/3.txt"
              "https://github.com/DandelionSprout/adfilt/raw/master/LegitimateURLShortener.txt"
              # ...
              # ...
              # ...
            ];
            */
            # externalLists = lib.concatStringsSep "\n" importedLists;
          };
          selectedFilterLists = [
            # ...
            "ublock-filters"
            "ublock-badware"
            "ublock-privacy"
            "ublock-unbreak"
            "ublock-quick-fixes"
            # "user-filters" # "importedLists" & "externalLists"?
            "adguard-generic"
            "adguard-mobile"
            "easylist"
            "adguard-spyware-url"
            "adguard-spyware"
            "block-lan"
            "easyprivacy"
            "urlhaus-1"
            "curben-phishing"
            "adguard-cookies"
            "ublock-cookies-adguard"
            "fanboy-cookiemonster"
            "ublock-cookies-easylist"
            "adguard-social"
            "fanboy-social"
            "fanboy-thirdparty_social"
            "adguard-popup-overlays"
            "adguard-mobile-app-banners"
            "adguard-other-annoyances"
            "adguard-widgets"
            "easylist-annoyances"
            "easylist-chat"
            "easylist-newsletters"
            "easylist-notifications"
            "ublock-annoyances"
            "dpollock-0"
            "plowe-0"
            "CHN-0"
            "DEU-0"
            "IND-0"
            "NLD-0"
            "NOR-0"
            "RUS-0"
            "RUS-1"
            "spa-0"
            "spa-1"
            # ...
            # ...
            # ...
          ];
        };
        # ...
        # ...
        # ...
      };
    };
  };

kinda ashamed i even posted this. this is the best i can do for now… please dont use this as-is, it may not be very secure, especially because these need to be updated on a weekly basis!

anyway, maybe this thread below is of usefulness?