diff --git a/.github/ISSUE_TEMPLATE/formatting.md b/.github/ISSUE_TEMPLATE/formatting.md
index 8e49b6b6f..f2a21f21f 100644
--- a/.github/ISSUE_TEMPLATE/formatting.md
+++ b/.github/ISSUE_TEMPLATE/formatting.md
@@ -26,7 +26,7 @@ Don't fill the form below manually! Let a program create a report for you:
 
 -->
 
-**Prettier 2.8.3**
+**Prettier 2.8.4**
 [Playground link](https://prettier.io/playground/#.....)
 
 ```sh
diff --git a/.github/ISSUE_TEMPLATE/integration.md b/.github/ISSUE_TEMPLATE/integration.md
index 239aba6e9..58f004f6c 100644
--- a/.github/ISSUE_TEMPLATE/integration.md
+++ b/.github/ISSUE_TEMPLATE/integration.md
@@ -20,7 +20,7 @@ BEFORE SUBMITTING AN ISSUE:
 
 **Environments:**
 
-- Prettier Version: 2.8.3
+- Prettier Version: 2.8.4
 - Running Prettier via: <!-- CLI, Node.js API, Browser API, etc. -->
 - Runtime: <!-- Node.js v14, Chrome v83, etc. -->
 - Operating System: <!-- Windows, Linux, macOS, etc. -->
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2a47b3eff..92259f95c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,126 @@
+# 2.8.4
+
+[diff](https://github.com/prettier/prettier/compare/2.8.3...2.8.4)
+
+#### Fix leading comments in mapped types with `readonly` ([#13427](https://github.com/prettier/prettier/pull/13427) by [@thorn0](https://github.com/thorn0), [@sosukesuzuki](https://github.com/sosukesuzuki))
+
+<!-- prettier-ignore -->
+```tsx
+// Input
+type Type = {
+  // comment
+  readonly [key in Foo];
+};
+
+// Prettier 2.8.3
+type Type = {
+  readonly // comment
+  [key in Foo];
+};
+
+// Prettier 2.8.4
+type Type = {
+  // comment
+  readonly [key in Foo];
+};
+```
+
+#### Group params in opening block statements ([#14067](https://github.com/prettier/prettier/pull/14067) by [@jamescdavis](https://github.com/jamescdavis))
+
+This is a follow-up to #13930 to establish wrapping consistency between opening block statements and else blocks by
+grouping params in opening blocks. This causes params to break to a new line together and not be split across lines
+unless the length of params exceeds the print width. This also updates the else block wrapping to behave exactly the
+same as opening blocks.
+
+<!-- prettier-ignore -->
+```hbs
+{{! Input }}
+{{#block param param param param param param param param param param as |blockParam|}}
+  Hello
+{{else block param param param param param param param param param param as |blockParam|}}
+  There
+{{/block}}
+
+{{! Prettier 2.8.3 }}
+{{#block
+  param
+  param
+  param
+  param
+  param
+  param
+  param
+  param
+  param
+  param
+  as |blockParam|
+}}
+  Hello
+{{else block param
+param
+param
+param
+param
+param
+param
+param
+param
+param}}
+  There
+{{/block}}
+
+{{! Prettier 2.8.4 }}
+{{#block
+  param param param param param param param param param param
+  as |blockParam|
+}}
+  Hello
+{{else block
+  param param param param param param param param param param
+  as |blockParam|
+}}
+  There
+{{/block}}
+```
+
+#### Ignore files in `.sl/` ([#14206](https://github.com/prettier/prettier/pull/14206) by [@bolinfest](https://github.com/bolinfest))
+
+In [Sapling SCM](https://sapling-scm.com/), `.sl/` is the folder where it stores its state, analogous to `.git/` in Git. It should be ignored in Prettier like the other SCM folders.
+
+#### Recognize `@satisfies` in Closure-style type casts ([#14262](https://github.com/prettier/prettier/pull/14262) by [@fisker](https://github.com/fisker))
+
+<!-- prettier-ignore -->
+```jsx
+// Input
+const a = /** @satisfies {Record<string, string>} */ ({hello: 1337});
+const b = /** @type {Record<string, string>} */ ({hello: 1337});
+
+// Prettier 2.8.3
+const a = /** @satisfies {Record<string, string>} */ { hello: 1337 };
+const b = /** @type {Record<string, string>} */ ({ hello: 1337 });
+
+// Prettier 2.8.4
+const a = /** @satisfies {Record<string, string>} */ ({hello: 1337});
+const b = /** @type {Record<string, string>} */ ({hello: 1337});
+```
+
+#### Fix parens in inferred function return types with `extends` ([#14279](https://github.com/prettier/prettier/pull/14279) by [@fisker](https://github.com/fisker))
+
+<!-- prettier-ignore -->
+```ts
+// Input
+type Foo<T> = T extends ((a) => a is infer R extends string) ? R : never;
+
+// Prettier 2.8.3 (First format)
+type Foo<T> = T extends (a) => a is infer R extends string ? R : never;
+
+// Prettier 2.8.3 (Second format)
+SyntaxError: '?' expected. 
+
+// Prettier 2.8.4
+type Foo<T> = T extends ((a) => a is infer R extends string) ? R : never;
+```
+
 # 2.8.3
 
 [diff](https://github.com/prettier/prettier/compare/2.8.2...2.8.3)
diff --git a/docs/browser.md b/docs/browser.md
index f55a8a773..da1e69b7d 100644
--- a/docs/browser.md
+++ b/docs/browser.md
@@ -20,8 +20,8 @@ Required options:
 
 - **`plugins`**: Unlike the `format` function from the [Node.js-based API](api.md#prettierformatsource--options), this function doesn’t load plugins automatically. The `plugins` option is required because all the parsers included in the Prettier package come as plugins (for reasons of file size). These plugins are files named
 
-  - `parser-*.js` in <https://unpkg.com/browse/prettier@2.8.3/> and
-  - `parser-*.mjs` in <https://unpkg.com/browse/prettier@2.8.3/esm/>
+  - `parser-*.js` in <https://unpkg.com/browse/prettier@2.8.4/> and
+  - `parser-*.mjs` in <https://unpkg.com/browse/prettier@2.8.4/esm/>
 
   You need to load the ones that you’re going to use and pass them to `prettier.format` using the `plugins` option.
 
@@ -32,8 +32,8 @@ See below for examples.
 ### Global
 
 ```html
-<script src="https://unpkg.com/prettier@2.8.3/standalone.js"></script>
-<script src="https://unpkg.com/prettier@2.8.3/parser-graphql.js"></script>
+<script src="https://unpkg.com/prettier@2.8.4/standalone.js"></script>
+<script src="https://unpkg.com/prettier@2.8.4/parser-graphql.js"></script>
 <script>
   prettier.format("type Query { hello: String }", {
     parser: "graphql",
@@ -48,8 +48,8 @@ Note that the [`unpkg` field](https://unpkg.com/#examples) in Prettier’s `pack
 
 ```html
 <script type="module">
-  import prettier from "https://unpkg.com/prettier@2.8.3/esm/standalone.mjs";
-  import parserGraphql from "https://unpkg.com/prettier@2.8.3/esm/parser-graphql.mjs";
+  import prettier from "https://unpkg.com/prettier@2.8.4/esm/standalone.mjs";
+  import parserGraphql from "https://unpkg.com/prettier@2.8.4/esm/parser-graphql.mjs";
 
   prettier.format("type Query { hello: String }", {
     parser: "graphql",
@@ -62,8 +62,8 @@ Note that the [`unpkg` field](https://unpkg.com/#examples) in Prettier’s `pack
 
 ```js
 define([
-  "https://unpkg.com/prettier@2.8.3/standalone.js",
-  "https://unpkg.com/prettier@2.8.3/parser-graphql.js",
+  "https://unpkg.com/prettier@2.8.4/standalone.js",
+  "https://unpkg.com/prettier@2.8.4/parser-graphql.js",
 ], (prettier, ...plugins) => {
   prettier.format("type Query { hello: String }", {
     parser: "graphql",
@@ -88,8 +88,8 @@ This syntax doesn’t necessarily work in the browser, but it can be used when b
 ### Worker
 
 ```js
-importScripts("https://unpkg.com/prettier@2.8.3/standalone.js");
-importScripts("https://unpkg.com/prettier@2.8.3/parser-graphql.js");
+importScripts("https://unpkg.com/prettier@2.8.4/standalone.js");
+importScripts("https://unpkg.com/prettier@2.8.4/parser-graphql.js");
 prettier.format("type Query { hello: String }", {
   parser: "graphql",
   plugins: prettierPlugins,
@@ -102,8 +102,8 @@ If you want to format [embedded code](options.md#embedded-language-formatting),
 
 ```html
 <script type="module">
-  import prettier from "https://unpkg.com/prettier@2.8.3/esm/standalone.mjs";
-  import parserBabel from "https://unpkg.com/prettier@2.8.3/esm/parser-babel.mjs";
+  import prettier from "https://unpkg.com/prettier@2.8.4/esm/standalone.mjs";
+  import parserBabel from "https://unpkg.com/prettier@2.8.4/esm/parser-babel.mjs";
 
   console.log(
     prettier.format("const html=/* HTML */ `<DIV> </DIV>`", {
@@ -119,9 +119,9 @@ The HTML code embedded in JavaScript stays unformatted because the `html` parser
 
 ```html
 <script type="module">
-  import prettier from "https://unpkg.com/prettier@2.8.3/esm/standalone.mjs";
-  import parserBabel from "https://unpkg.com/prettier@2.8.3/esm/parser-babel.mjs";
-  import parserHtml from "https://unpkg.com/prettier@2.8.3/esm/parser-html.mjs";
+  import prettier from "https://unpkg.com/prettier@2.8.4/esm/standalone.mjs";
+  import parserBabel from "https://unpkg.com/prettier@2.8.4/esm/parser-babel.mjs";
+  import parserHtml from "https://unpkg.com/prettier@2.8.4/esm/parser-html.mjs";
 
   console.log(
     prettier.format("const html=/* HTML */ `<DIV> </DIV>`", {
diff --git a/package.json b/package.json
index 20f95475d..96c0befd9 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "prettier",
-  "version": "2.9.0-dev",
+  "version": "2.8.4",
   "description": "Prettier is an opinionated code formatter",
   "bin": "./bin/prettier.js",
   "repository": "prettier/prettier",
diff --git a/website/versioned_docs/version-stable/browser.md b/website/versioned_docs/version-stable/browser.md
index 73237cc17..733ae11e9 100644
--- a/website/versioned_docs/version-stable/browser.md
+++ b/website/versioned_docs/version-stable/browser.md
@@ -21,8 +21,8 @@ Required options:
 
 - **`plugins`**: Unlike the `format` function from the [Node.js-based API](api.md#prettierformatsource--options), this function doesn’t load plugins automatically. The `plugins` option is required because all the parsers included in the Prettier package come as plugins (for reasons of file size). These plugins are files named
 
-  - `parser-*.js` in <https://unpkg.com/browse/prettier@2.8.3/> and
-  - `parser-*.mjs` in <https://unpkg.com/browse/prettier@2.8.3/esm/>
+  - `parser-*.js` in <https://unpkg.com/browse/prettier@2.8.4/> and
+  - `parser-*.mjs` in <https://unpkg.com/browse/prettier@2.8.4/esm/>
 
   You need to load the ones that you’re going to use and pass them to `prettier.format` using the `plugins` option.
 
@@ -33,8 +33,8 @@ See below for examples.
 ### Global
 
 ```html
-<script src="https://unpkg.com/prettier@2.8.3/standalone.js"></script>
-<script src="https://unpkg.com/prettier@2.8.3/parser-graphql.js"></script>
+<script src="https://unpkg.com/prettier@2.8.4/standalone.js"></script>
+<script src="https://unpkg.com/prettier@2.8.4/parser-graphql.js"></script>
 <script>
   prettier.format("type Query { hello: String }", {
     parser: "graphql",
@@ -49,8 +49,8 @@ Note that the [`unpkg` field](https://unpkg.com/#examples) in Prettier’s `pack
 
 ```html
 <script type="module">
-  import prettier from "https://unpkg.com/prettier@2.8.3/esm/standalone.mjs";
-  import parserGraphql from "https://unpkg.com/prettier@2.8.3/esm/parser-graphql.mjs";
+  import prettier from "https://unpkg.com/prettier@2.8.4/esm/standalone.mjs";
+  import parserGraphql from "https://unpkg.com/prettier@2.8.4/esm/parser-graphql.mjs";
 
   prettier.format("type Query { hello: String }", {
     parser: "graphql",
@@ -63,8 +63,8 @@ Note that the [`unpkg` field](https://unpkg.com/#examples) in Prettier’s `pack
 
 ```js
 define([
-  "https://unpkg.com/prettier@2.8.3/standalone.js",
-  "https://unpkg.com/prettier@2.8.3/parser-graphql.js",
+  "https://unpkg.com/prettier@2.8.4/standalone.js",
+  "https://unpkg.com/prettier@2.8.4/parser-graphql.js",
 ], (prettier, ...plugins) => {
   prettier.format("type Query { hello: String }", {
     parser: "graphql",
@@ -89,8 +89,8 @@ This syntax doesn’t necessarily work in the browser, but it can be used when b
 ### Worker
 
 ```js
-importScripts("https://unpkg.com/prettier@2.8.3/standalone.js");
-importScripts("https://unpkg.com/prettier@2.8.3/parser-graphql.js");
+importScripts("https://unpkg.com/prettier@2.8.4/standalone.js");
+importScripts("https://unpkg.com/prettier@2.8.4/parser-graphql.js");
 prettier.format("type Query { hello: String }", {
   parser: "graphql",
   plugins: prettierPlugins,
@@ -103,8 +103,8 @@ If you want to format [embedded code](options.md#embedded-language-formatting),
 
 ```html
 <script type="module">
-  import prettier from "https://unpkg.com/prettier@2.8.3/esm/standalone.mjs";
-  import parserBabel from "https://unpkg.com/prettier@2.8.3/esm/parser-babel.mjs";
+  import prettier from "https://unpkg.com/prettier@2.8.4/esm/standalone.mjs";
+  import parserBabel from "https://unpkg.com/prettier@2.8.4/esm/parser-babel.mjs";
 
   console.log(
     prettier.format("const html=/* HTML */ `<DIV> </DIV>`", {
@@ -120,9 +120,9 @@ The HTML code embedded in JavaScript stays unformatted because the `html` parser
 
 ```html
 <script type="module">
-  import prettier from "https://unpkg.com/prettier@2.8.3/esm/standalone.mjs";
-  import parserBabel from "https://unpkg.com/prettier@2.8.3/esm/parser-babel.mjs";
-  import parserHtml from "https://unpkg.com/prettier@2.8.3/esm/parser-html.mjs";
+  import prettier from "https://unpkg.com/prettier@2.8.4/esm/standalone.mjs";
+  import parserBabel from "https://unpkg.com/prettier@2.8.4/esm/parser-babel.mjs";
+  import parserHtml from "https://unpkg.com/prettier@2.8.4/esm/parser-html.mjs";
 
   console.log(
     prettier.format("const html=/* HTML */ `<DIV> </DIV>`", {