From aa98a454e8544709b817d9623e623ef8e1d3b368 Mon Sep 17 00:00:00 2001
From: princejain756 <princejain756@gmail.com>
Date: Wed, 21 Oct 2026 12:19:58 +0530
Subject: [PATCH] fix(res.redirect): add Content-Length only if
 Transfer-Encoding is not present

res.redirect() always set Content-Length, even when Transfer-Encoding was already set. That is the same conflict #4893 fixed for res.send(), and Node's HTTP client rejects such responses with a parse error. Apply the same guard as res.send(): Content-Length is only set when no Transfer-Encoding header is present. Fixes #7506.
---
 lib/response.js      |  6 +++++-
 test/res.redirect.js | 26 ++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/lib/response.js b/lib/response.js
index 0d5a4ae4d4d..7f6d0664e97 100644
--- a/lib/response.js
+++ b/lib/response.js
@@ -857,7 +857,11 @@ res.redirect = function redirect(url) {
 
   // Respond
   this.status(status);
-  this.set('Content-Length', Buffer.byteLength(body));
+  // Because Content-Length and Transfer-Encoding can't be present in the response headers together,
+  // Content-Length should be added only if there is no Transfer-Encoding header
+  if (!this.get('Transfer-Encoding')) {
+    this.set('Content-Length', Buffer.byteLength(body));
+  }
 
   if (this.req.method === 'HEAD') {
     this.end();
diff --git a/test/res.redirect.js b/test/res.redirect.js
index 8d2b164e4a2..cad1d2fcf3c 100644
--- a/test/res.redirect.js
+++ b/test/res.redirect.js
@@ -78,6 +78,32 @@ describe('res', function(){
     })
   })
 
+  describe('when Transfer-Encoding header is present', function(){
+    var transferEncodings = [
+      'chunked',
+      'compress',
+      'deflate',
+      'gzip'
+    ];
+
+    transferEncodings.forEach(function(encoding){
+      it('should not add Content-Length header if Transfer-Encoding header is equal to ' + encoding, function(done){
+        var app = express();
+
+        app.use(function(req, res){
+          res.set('Transfer-Encoding', encoding).redirect('http://google.com');
+        });
+
+        request(app)
+          .get('/')
+          .expect(utils.shouldNotHaveHeader('Content-Length'))
+          .expect(utils.shouldHaveHeader('Transfer-Encoding'))
+          .expect('Location', 'http://google.com')
+          .expect(302, done);
+      })
+    })
+  })
+
   describe('when accepting html', function(){
     it('should respond with html', function(done){
       var app = express();