diff --git a/doc/release-notes/rl-2605.section.md b/doc/release-notes/rl-2605.section.md
index b3a9039d0e12..977257a4f513 100644
--- a/doc/release-notes/rl-2605.section.md
+++ b/doc/release-notes/rl-2605.section.md
@@ -74,6 +74,8 @@
 
 - `lima` has been updated from `1.x` to `2.x`. This major update includes several breaking changes, such as `/tmp/lima` no longer being mounted by default.
 
+- `mercure` has been update to `0.21.4` (or later). Version [0.21.0](https://github.com/dunglas/mercure/releases/v0.21.0) and [0.21.2](https://github.com/dunglas/mercure/releases/tag/v0.21.2) introduce breaking changes to the package.
+
 - `n8n` has been updated to version 2. You can find the breaking changes here: https://docs.n8n.io/2-0-breaking-changes/.
 
 - `gurk-rs` has been updated from `0.6.4` to `0.8.0`. Version `0.8.0` includes breaking changes. For more information read the [release notes for 0.8.0](https://github.com/boxdot/gurk-rs/releases/tag/v0.8.0).
diff --git a/pkgs/by-name/me/mercure/package.nix b/pkgs/by-name/me/mercure/package.nix
index 2bc37aedd623..df031e5b6242 100644
--- a/pkgs/by-name/me/mercure/package.nix
+++ b/pkgs/by-name/me/mercure/package.nix
@@ -9,18 +9,18 @@
 
 buildGoModule rec {
   pname = "mercure";
-  version = "0.20.2";
+  version = "0.21.6";
 
   src = fetchFromGitHub {
     owner = "dunglas";
     repo = "mercure";
     rev = "v${version}";
-    hash = "sha256-DmeBnvJhGYtEGoJDey8+Bb7MuP+Y1GLtQHg6QLoAzv4=";
+    hash = "sha256-hCEoEs6NiShssKER1Z8IVQPF+Ir7wbreGInWmcdnqzE=";
   };
 
   sourceRoot = "${src.name}/caddy";
 
-  vendorHash = "sha256-ZisV7+Mo8TMN+AUGPKHzEluzEShxZCuXrnYgySi57TY=";
+  vendorHash = "sha256-GTHJtNO4JqTEDxVMe0yTgnjhfK2aGZpjMTfSFtL29IU=";
 
   subPackages = [ "mercure" ];
   excludedPackages = [ "../cmd/mercure" ];