From 3529f97899453ca809e0dd233b208754c32f2420 Mon Sep 17 00:00:00 2001
From: Prakash <qxprakash@gmail.com>
Date: Tue, 3 Feb 2026 15:18:38 +0530
Subject: [PATCH] fix signature mismatch in @uppy/aws-s3 (#6165)

shouldUseMultipart: true was not working due to signature mismatch

AI summary :

This pull request improves support for specifying the `contentType`
during S3 uploads, ensuring that the correct content type is set when
generating presigned URLs for both single and multipart uploads. It also
updates the client-side and server-side code to handle this new
parameter.

**Backend and API enhancements:**
- Updated the `/s3/presign` endpoint in `index.js` to accept an optional
`contentType` parameter and to include it in the S3 `PutObjectCommand`
and `CreateMultipartUploadCommand` requests, defaulting to
`'application/octet-stream'` if not provided.
[[1]](diffhunk://#diff-0c4471088c62917198e1438777b4c7e78fd4d87d450d2a7c78b86b7c647ac97bL360-R360)
[[2]](diffhunk://#diff-0c4471088c62917198e1438777b4c7e78fd4d87d450d2a7c78b86b7c647ac97bR384-R391)

**Client-side and types improvements:**
- Added `contentType` to the `presignableRequest` type to ensure type
safety and clarity when passing this parameter.
- Modified the S3 client (`S3.ts`) to include `contentType` when making
presign requests.
- Updated the example HTML (`rewrite-test.html`) to send `contentType`
in presign requests and enabled multipart uploads for testing.
[[1]](diffhunk://#diff-ca9bc28a71d2d8ac4e0aa6844698f2244594a12e695fc3e153db36674ccb2b52L103-R103)
[[2]](diffhunk://#diff-ca9bc28a71d2d8ac4e0aa6844698f2244594a12e695fc3e153db36674ccb2b52R114)
---
 examples/aws-nodejs/index.js                 | 4 +++-
 examples/aws-nodejs/public/rewrite-test.html | 3 +--
 packages/@uppy/aws-s3/src/s3-client/S3.ts    | 1 +
 packages/@uppy/aws-s3/src/s3-client/types.ts | 1 +
 4 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/examples/aws-nodejs/index.js b/examples/aws-nodejs/index.js
index febb4f810..ae496293b 100644
--- a/examples/aws-nodejs/index.js
+++ b/examples/aws-nodejs/index.js
@@ -357,7 +357,7 @@ app.delete('/s3/multipart/:uploadId', (req, res, next) => {
 
 app.post('/s3/presign', async (req, res, next) => {
   try {
-    const { method, key, uploadId, partNumber } = req.body
+    const { method, key, uploadId, partNumber, contentType } = req.body
     const client = getS3Client()
 
     if (!method || !key) {
@@ -381,12 +381,14 @@ app.post('/s3/presign', async (req, res, next) => {
       command = new PutObjectCommand({
         Bucket: bucket,
         Key: key,
+        ContentType: contentType || 'application/octet-stream',
       })
     } else if (method === 'POST' && !uploadId) {
       // CreateMultipartUpload
       command = new CreateMultipartUploadCommand({
         Bucket: bucket,
         Key: key,
+        ContentType: contentType || 'application/octet-stream',
       })
     } else if (method === 'POST' && uploadId) {
       // CompleteMultipartUpload
diff --git a/examples/aws-nodejs/public/rewrite-test.html b/examples/aws-nodejs/public/rewrite-test.html
index 3833fb9e2..350c19370 100644
--- a/examples/aws-nodejs/public/rewrite-test.html
+++ b/examples/aws-nodejs/public/rewrite-test.html
@@ -65,7 +65,6 @@
             id: 'AwsS3-STS',
             bucket: window.UPPY_S3_BUCKET, // Set by server
             region: window.UPPY_S3_REGION || 'us-east-1',
-
             // Get temporary credentials from /s3/sts
             getCredentials: async ({ signal }) => {
               const response = await fetch('/s3/sts', { signal })
@@ -100,7 +99,6 @@
             id: 'AwsS3-Sign',
             bucket: window.UPPY_S3_BUCKET,
             region: window.UPPY_S3_REGION || 'us-east-1',
-
             // Sign requests via /s3/presign endpoint (returns presigned URLs)
             signRequest: async (request) => {
               const response = await fetch('/s3/presign', {
@@ -111,6 +109,7 @@
                   key: request.key,
                   uploadId: request.uploadId,
                   partNumber: request.partNumber,
+                  contentType: request.contentType,
                 }),
               })
               if (!response.ok) throw new Error('Failed to get presigned URL')
diff --git a/packages/@uppy/aws-s3/src/s3-client/S3.ts b/packages/@uppy/aws-s3/src/s3-client/S3.ts
index d26e3df2f..676cf02b7 100644
--- a/packages/@uppy/aws-s3/src/s3-client/S3.ts
+++ b/packages/@uppy/aws-s3/src/s3-client/S3.ts
@@ -236,6 +236,7 @@ class S3mini {
       key,
       uploadId,
       partNumber,
+      contentType,
     })
 
     // Build request headers
diff --git a/packages/@uppy/aws-s3/src/s3-client/types.ts b/packages/@uppy/aws-s3/src/s3-client/types.ts
index 8a2b51251..227efd3ab 100644
--- a/packages/@uppy/aws-s3/src/s3-client/types.ts
+++ b/packages/@uppy/aws-s3/src/s3-client/types.ts
@@ -5,6 +5,7 @@ export type presignableRequest = {
   uploadId?: string
   partNumber?: number
   expiresIn?: number
+  contentType?: string
 }
 
 /** Response with the pre-signed URL */