diff --git a/nixos/doc/manual/release-notes/rl-2611.section.md b/nixos/doc/manual/release-notes/rl-2611.section.md
index 2f59613ac859..db84a50d3697 100644
--- a/nixos/doc/manual/release-notes/rl-2611.section.md
+++ b/nixos/doc/manual/release-notes/rl-2611.section.md
@@ -396,6 +396,12 @@
 
 - `services.porn-vault.settings` may need changes when using non-default options, due to upstream changes. Chack the new default module config for reference.
 
+- Flarum 2 is now available as `pkgs.flarum_2`. Flarum 1 has moved to `pkgs.flarum_1`, and `pkgs.flarum` is now a deprecated alias for it. [`services.flarum.package`](#opt-services.flarum.package) now defaults to:
+  - `pkgs.flarum_1` if [`system.stateVersion`](#opt-system.stateVersion) is older than 26.11, so existing installations keep running Flarum 1;
+  - `pkgs.flarum_2` otherwise.
+
+  Switching an existing installation to `pkgs.flarum_2` upgrades its database in place, which can't be undone. Back up the database first, and make sure every installed extension has a release for Flarum 2.
+
 ## Other Notable Changes {#sec-release-26.11-notable-changes}
 
 <!-- To avoid merge conflicts, consider adding your item at an arbitrary place in the list instead. -->
diff --git a/nixos/modules/services/web-apps/flarum.nix b/nixos/modules/services/web-apps/flarum.nix
index ad5e093486ec..0ffa76ffdec2 100644
--- a/nixos/modules/services/web-apps/flarum.nix
+++ b/nixos/modules/services/web-apps/flarum.nix
@@ -66,7 +66,24 @@ in
   options.services.flarum = {
     enable = mkEnableOption "Flarum discussion platform";
 
-    package = mkPackageOption pkgs "flarum" { };
+    package = mkOption {
+      type = types.package;
+      default = if versionOlder config.system.stateVersion "26.11" then pkgs.flarum_1 else pkgs.flarum_2;
+      defaultText = literalExpression ''
+        if versionOlder config.system.stateVersion "26.11" then pkgs.flarum_1 else pkgs.flarum_2
+      '';
+      relatedPackages = [
+        "flarum_1"
+        "flarum_2"
+      ];
+      description = ''
+        Flarum package to use.
+
+        Upgrading from Flarum 1.x to 2.x migrates the database and can't be
+        undone, so back up the database and make sure all extensions support
+        Flarum 2 before switching.
+      '';
+    };
 
     forumTitle = mkOption {
       type = types.str;
diff --git a/nixos/tests/all-tests.nix b/nixos/tests/all-tests.nix
index fceae8099fb1..5b7997ccd583 100644
--- a/nixos/tests/all-tests.nix
+++ b/nixos/tests/all-tests.nix
@@ -689,7 +689,14 @@ in
   flannel = runTestOn [ "x86_64-linux" ] ./flannel.nix;
   flap-alerted = runTest ./flap-alerted.nix;
   flaresolverr = runTest ./flaresolverr.nix;
-  flarum = runTest ./flarum.nix;
+  flarum_1 = runTest {
+    imports = [ ./flarum.nix ];
+    _module.args.package = pkgs.flarum_1;
+  };
+  flarum_2 = runTest {
+    imports = [ ./flarum.nix ];
+    _module.args.package = pkgs.flarum_2;
+  };
   flood = runTest ./flood.nix;
   fluent-bit = runTest ./fluent-bit.nix;
   fluentd = runTest ./fluentd.nix;
diff --git a/nixos/tests/flarum.nix b/nixos/tests/flarum.nix
index 3157a0627577..1679cc09aab1 100644
--- a/nixos/tests/flarum.nix
+++ b/nixos/tests/flarum.nix
@@ -1,6 +1,6 @@
-{ lib, ... }:
+{ lib, package, ... }:
 {
-  name = "flarum";
+  name = "flarum-${package.version}";
 
   meta = {
     maintainers = with lib.maintainers; [
@@ -18,6 +18,7 @@
 
       services.flarum = {
         enable = true;
+        inherit package;
         forumTitle = "NixOS Flarum Test Forum";
         domain = "localhost";
         baseUrl = "http://localhost";
diff --git a/pkgs/by-name/fl/flarum/composer.lock b/pkgs/by-name/fl/flarum_1/composer.lock
similarity index 100%
rename from pkgs/by-name/fl/flarum/composer.lock
rename to pkgs/by-name/fl/flarum_1/composer.lock
diff --git a/pkgs/by-name/fl/flarum/package.nix b/pkgs/by-name/fl/flarum_1/package.nix
similarity index 85%
rename from pkgs/by-name/fl/flarum/package.nix
rename to pkgs/by-name/fl/flarum_1/package.nix
index 975f1f086de8..2e2d3c243a36 100644
--- a/pkgs/by-name/fl/flarum/package.nix
+++ b/pkgs/by-name/fl/flarum_1/package.nix
@@ -6,6 +6,8 @@
 }:
 
 php.buildComposerProject2 (finalAttrs: {
+  __structuredAttrs = true;
+
   pname = "flarum";
   version = "1.8.19";
 
@@ -21,10 +23,10 @@ php.buildComposerProject2 (finalAttrs: {
   composerLock = ./composer.lock;
   vendorHash = "sha256-EXKQ9x7E15Fc4fu/XdjlgMDCpmvg1XupBGq13WDspDI=";
 
-  passthru.tests.module = nixosTests.flarum;
+  passthru.tests.module = nixosTests.flarum_1;
 
   meta = {
-    changelog = "https://github.com/flarum/framework/blob/main/CHANGELOG.md";
+    changelog = "https://github.com/flarum/framework/blob/1.x/CHANGELOG.md";
     description = "Delightfully simple discussion platform for your website";
     homepage = "https://github.com/flarum/flarum";
     license = lib.licenses.mit;
diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index a140fabc2217..33b494022221 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -886,6 +886,7 @@ mapAliases {
   fishy = throw "'fishy' has been removed because it was unmaintained upstream"; # Added 2026-08-18
   fit-trackee = throw "'fit-trackee' has been renamed to/replaced by 'fittrackee'"; # Converted to throw 2025-10-27
   fixup_yarn_lock = throw "`fixup_yarn_lock` has been removed, please use `fixup-yarn-lock` instead."; # Added 2026-04-25
+  flarum = warnAlias "'flarum' has been renamed to 'flarum_1'. Use 'flarum_1', or 'flarum_2' to upgrade (this migrates the database and can't be undone)." flarum_1; # Added 2026-10-14
   flashrom-stable = throw "'flashrom-stable' has been renamed to/replaced by 'flashprog'"; # Converted to throw 2025-10-27
   flatbuffers_2_0 = throw "'flatbuffers_2_0' has been renamed to/replaced by 'flatbuffers'"; # Converted to throw 2025-10-27
   flattenReferencesGraph = warnAlias "'flattenReferencesGraph' has been renamed to 'flatten-references-graph'" flatten-references-graph; # Added 2026-02-08