1.21.1 release notes

Author: VesaJuvonen

docs/spfx/release-1.21.1.md

@@ -0,0 +1,53 @@
+---
+title: SharePoint Framework v1.21.1 release notes
+description: Release notes for the SharePoint Framework v1.21.1 release
+ms.date: 05/03/2025
+ms.localizationpriority: high
+---
+# SharePoint Framework v1.21.1 release notes
+
+This is a _minor bump_ that fixes the issues around SharePoint Framework solution packaging, provides a fix on a regression related on the CSS handling with the previous [released 1.21 version](release-1.21.md).
+
+> [!TIP]
+> It's safe to keep on using SharePoint Framework 1.21 version (if you don't have CSS issues with it), but we do recommend using always the latest version in the production, which in this case would be the 1.17.1, which has fixes on the reported GitHub issues as listed below.
+
+**Released:** May 3, 2025
+
+[!INCLUDE [spfx-release-notes-common](../../includes/snippets/spfx-release-notes-common.md)]
+
+## Install the latest version
+
+Install the latest release of the SharePoint Framework (SPFx) by including the **@latest** tag:
+
+```console
+npm install @microsoft/generator-sharepoint@next --global
+```
+
+## Upgrading projects from v1.21 to v1.21.1
+
+In the project's **package.json** file, identify all SPFx v1.21 packages. For each SPFx package:
+
+1. Uninstall the existing v1.21 package:
+
+    ```console
+    npm uninstall @microsoft/{spfx-package-name}@1.21
+    ```
+
+1. Install the new v1.21.1 package:
+
+    ```console
+    npm install @microsoft/{spfx-package-name}@latest --save --save-exact
+    ```
+
+[!INCLUDE [spfx-release-upgrade-tip](../../includes/snippets/spfx-release-upgrade-tip.md)]
+
+## Fixed Issues
+
+Here's a list of specific issues fixed around SharePoint Framework since the previous public release.
+
+- [#10205](https://github.com/SharePoint/sp-dev-docs/issues/10205) - SPFx 1.21 - SCSS/CSS Module hashes being applied twice, styling not working
+- [#10207](https://github.com/SharePoint/sp-dev-docs/issues/10207) - SPFx - Styles not being applied in newest version of SPFx 1.21
+
+Also following issue has been fixed and the server side update is currently rolling in production. This means that the fix will be applied on server side without changes on the client side packages.
+
+- [#10053](https://github.com/SharePoint/sp-dev-docs/issues/10053) - Web Part Missing in Toolbox After Running Gulp Serve

docs/toc.yml

@@ -474,8 +474,10 @@
     items:
     - name: Overview
       href: spfx/roadmap.md
+    - name: SPFx v1.21 - May 3, 2025
+      href: spfx/release-1.21.1.md
     - name: SPFx v1.21 - April 23, 2025
-      href: spfx/release-1.21.md        
+      href: spfx/release-1.21.md
     - name: SPFx v1.20 - September 26, 2024
       href: spfx/release-1.20.md
     - name: SPFx v1.19 - April 25, 2024