From 6f6fdf08bc13b61acd811173312d61806e3cab37 Mon Sep 17 00:00:00 2001
From: Nicolas Grekas <nicolas.grekas@gmail.com>
Date: Mon, 23 Jun 2025 17:15:50 +0200
Subject: [PATCH] [HttpFoundation] Deprecate using `Request::sendHeaders()`
 after headers have already been sent

---
 UPGRADE-7.4.md                                    | 5 +++++
 src/Symfony/Component/HttpFoundation/CHANGELOG.md | 5 +++++
 src/Symfony/Component/HttpFoundation/Response.php | 3 ++-
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/UPGRADE-7.4.md b/UPGRADE-7.4.md
index 487bf6f5007a6..859fd57d0afa6 100644
--- a/UPGRADE-7.4.md
+++ b/UPGRADE-7.4.md
@@ -22,3 +22,8 @@ HttpClient
 ----------
 
  * Deprecate using amphp/http-client < 5
+
+HttpFoundation
+--------------
+
+ * Deprecate using `Request::sendHeaders()` after headers have already been sent; use a `StreamedResponse` instead
diff --git a/src/Symfony/Component/HttpFoundation/CHANGELOG.md b/src/Symfony/Component/HttpFoundation/CHANGELOG.md
index 374c31889df3c..ca58a4032d8b8 100644
--- a/src/Symfony/Component/HttpFoundation/CHANGELOG.md
+++ b/src/Symfony/Component/HttpFoundation/CHANGELOG.md
@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+7.4
+---
+
+ * Deprecate using `Request::sendHeaders()` after headers have already been sent; use a `StreamedResponse` instead
+
 7.3
 ---
 
diff --git a/src/Symfony/Component/HttpFoundation/Response.php b/src/Symfony/Component/HttpFoundation/Response.php
index 455b026dffb05..173ee3f93eb3b 100644
--- a/src/Symfony/Component/HttpFoundation/Response.php
+++ b/src/Symfony/Component/HttpFoundation/Response.php
@@ -319,7 +319,8 @@ public function sendHeaders(?int $statusCode = null): static
         if (headers_sent()) {
             if (!\in_array(\PHP_SAPI, ['cli', 'phpdbg', 'embed'], true)) {
                 $statusCode ??= $this->statusCode;
-                header(\sprintf('HTTP/%s %s %s', $this->version, $statusCode, $this->statusText), true, $statusCode);
+                trigger_deprecation('symfony/http-foundation', '7.4', 'Trying to use "%s::sendHeaders()" after headers have already been sent is deprecated will throw a PHP warning in 8.0. Use a "StreamedResponse" instead.', static::class);
+                //header(\sprintf('HTTP/%s %s %s', $this->version, $statusCode, $this->statusText), true, $statusCode);
             }
 
             return $this;