diff --git a/UPLOAD_TROUBLESHOOTING.md b/UPLOAD_TROUBLESHOOTING.md
new file mode 100644
index 0000000..dba38ab
--- /dev/null
+++ b/UPLOAD_TROUBLESHOOTING.md
@@ -0,0 +1,364 @@
+# Ferrero OpenText DAM - Upload Troubleshooting Document
+
+**Date:** October 24, 2025
+**Environment:** Production (https://ppr.dam.ferrero.com)
+**Application:** Content Scaling Workflow V3
+**Issue:** File uploads blocked with "restricted file extension" error
+
+---
+
+## Executive Summary
+
+The Content Scaling workflow application successfully performs campaign management, asset downloads, and status updates. However, **all file upload attempts via the OpenText Media Management API are being rejected** with file extension restriction errors, regardless of file type.
+
+This document provides detailed technical information for Ferrero's OpenText DAM support team to diagnose and resolve the upload restriction.
+
+---
+
+## Current Status
+
+### ✅ Working Features
+
+1. **Campaign Discovery**
+   - Search campaigns by Content Scaling Status (A1, A2, A5, etc.)
+   - Filter by status using `CONTENT.SCALING.STATUS` metadata field
+   - Display campaign details, brands, markets
+
+2. **Asset Downloads**
+   - Download master assets from campaigns
+   - Bulk download functionality
+   - Multiple file format support (.tif, .jpg, .png, etc.)
+
+3. **Status Management**
+   - Update campaign status: A1→A2, A2→A3, A5→A6
+   - Uses PATCH `/v6/folders/{id}?lock_strategy=optimistic`
+   - All status transitions working correctly
+
+4. **OAuth2 Authentication**
+   - Client credentials flow working
+   - Token refresh functioning
+   - Authorization headers properly included in all requests
+
+### ❌ Blocked Feature
+
+**File Uploads to DAM**
+- ALL file uploads rejected
+- Multiple file types tested
+- Various API approaches attempted
+- Consistent error across all attempts
+
+---
+
+## Upload Error Details
+
+### Error Message
+```json
+{
+  "exception_body": {
+    "http_response_code": 500,
+    "message": "Cannot import asset having restricted file extension.",
+    "debug_message": "Asset creation failed due to restricted file extension",
+    "error_code": 1000
+  }
+}
+```
+
+### API Endpoint Used
+```
+POST https://ppr.dam.ferrero.com/otmmapi/v6/assets
+```
+
+### Authentication
+- **Method:** OAuth2 Bearer Token
+- **Token Status:** Valid and active
+- **User:** scpi.user1 (from Creds.txt)
+- **Permissions:** Claimed to have "full access"
+
+---
+
+## File Types Tested
+
+All of the following file extensions were rejected with the same error:
+
+| File Extension | MIME Type | Test Result |
+|----------------|-----------|-------------|
+| `.tif` | image/tiff | ❌ Rejected |
+| `.jpg` | image/jpeg | ❌ Rejected |
+| `.png` | image/png | ❌ Rejected |
+| `.pdf` | application/pdf | ❌ Rejected |
+
+**Conclusion:** The restriction appears to be **account-level or API-level**, not file-type-specific.
+
+---
+
+## Upload Approaches Tested
+
+### Attempt 1: Full Metadata from Master Asset
+**Payload:**
+- `asset_representation` with complete metadata structure from existing master asset
+- `metadata_model_id`: ECOMMERCE (from master asset)
+- `security_policy_list`: From master asset
+- `manifest`: Upload manifest with filename and MIME type
+- `parent_folder_id`: Final Assets folder ID
+- `files`: File uploaded via CURLFile
+
+**Result:** HTTP 500 - "restricted file extension"
+
+---
+
+### Attempt 2: Minimal Metadata with Model ID
+**Payload:**
+- `asset_representation` with only:
+  - `name`: Filename
+  - `metadata_model_id`: ECOMMERCE
+  - `security_policy_list`: [{"id": 1594}]
+- `manifest`: Upload manifest
+- `parent_folder_id`: Final Assets folder ID
+- `files`: File
+
+**Result:** HTTP 500 - "restricted file extension"
+
+---
+
+### Attempt 3: Import Template Approach
+**Payload:**
+- `import_template_id`: MARKETING.ASSET
+- `manifest`: Upload manifest
+- `parent_folder_id`: Final Assets folder ID
+- `files`: File
+
+**Result:** HTTP 400 - "No permissable import template found"
+
+---
+
+### Attempt 4: Absolute Minimum (No Metadata)
+**Payload:**
+- `manifest`: Upload manifest only
+- `parent_folder_id`: Final Assets folder ID
+- `files`: File
+
+**Result:** HTTP 500 - "restricted file extension"
+
+---
+
+### Attempt 5: Without Metadata Model ID
+**Payload:**
+- `asset_representation`:
+  - `name`: Filename
+  - `security_policy_list`: [{"id": 1594}]
+- `manifest`: Upload manifest
+- `parent_folder_id`: Final Assets folder ID
+- `files`: File
+
+**Result:** HTTP 500 - "restricted file extension"
+
+---
+
+## Technical Details
+
+### Request Structure (Current Implementation)
+
+**Endpoint:**
+```
+POST /v6/assets
+```
+
+**Headers:**
+```
+Accept: application/json
+Authorization: Bearer {oauth_token}
+Content-Type: multipart/form-data
+```
+
+**Form Data Fields:**
+```
+asset_representation: {
+  "asset_resource": {
+    "asset": {
+      "name": "filename.jpg",
+      "metadata_model_id": "ECOMMERCE",
+      "security_policy_list": [{"id": 1594}]
+    }
+  }
+}
+
+manifest: {
+  "upload_manifest": {
+    "master_files": [{
+      "file": {
+        "file_name": "filename.jpg",
+        "file_type": "image/jpeg"
+      }
+    }]
+  }
+}
+
+parent_folder_id: "ea0dbf86e13e3634895746d3a986558ec2eb8be1"
+
+files: [binary file data via CURLFile]
+```
+
+### Upload Target Details
+
+**Campaign:** Local adaptation test 2 (C000000078)
+**Campaign Asset ID:** 7e2f7c97b003f91f8b2a162b9f62ccab51586fa9
+**Target Folder:** Final Assets (ID: ea0dbf86e13e3634895746d3a986558ec2eb8be1)
+**Content Scaling Status:** A2 (Assets Sent to Agency)
+
+**Master Assets Available:**
+- 8000500247167_8.tif (image/tiff, ECOMMERCE model)
+- [Additional assets in Master Assets folder]
+
+---
+
+## Comparison: Downloads vs Uploads
+
+### Downloads (Working ✅)
+- **Endpoint:** `GET /v6/assets/{id}/contents`
+- **Authentication:** Same OAuth token
+- **File Types:** .tif, .jpg, .png all download successfully
+- **Permissions:** Read access confirmed working
+
+### Uploads (Blocked ❌)
+- **Endpoint:** `POST /v6/assets`
+- **Authentication:** Same OAuth token
+- **File Types:** ALL rejected
+- **Permissions:** Upload/write access appears restricted
+
+**Analysis:** The same OAuth credentials work for downloads but not uploads, suggesting **write permissions may not be enabled** for the API user account.
+
+---
+
+## Questions for Ferrero DAM Support
+
+### 1. API Upload Permissions
+- Is the user account `scpi.user1` authorized to upload files via API?
+- Are there separate permissions for read vs. write operations?
+- Is there a different user account or API key required for uploads?
+
+### 2. File Extension Whitelist
+- What file extensions are permitted for uploads via `/v6/assets` endpoint?
+- Is there a server-side whitelist configuration?
+- Can this be configured per user or globally?
+
+### 3. Alternative Upload Methods
+- Is there a different API endpoint for uploads? (e.g., `/assets` without `/v6/`?)
+- Are there import templates we should be using instead of direct uploads?
+- What method does the web interface use for uploads?
+
+### 4. Metadata Requirements
+- What is the minimum required metadata structure for uploads?
+- Are specific metadata fields mandatory for the ECOMMERCE model?
+- Can uploads inherit metadata from the parent folder?
+
+### 5. Environment Configuration
+- Are API uploads enabled in the production environment?
+- Are there rate limits or quota restrictions?
+- Are uploads restricted to certain folders or campaigns?
+
+---
+
+## Additional Context
+
+### Master Asset Metadata Size Issue
+
+Master assets contain extensive metadata structures (brands, markets, campaigns, compliance data, etc.) that are **too large to transmit** in upload requests:
+- Causes PHP memory issues when stored in session
+- JSON payload becomes several MB in size
+- Server returns HTTP 502 (Bad Gateway) when full metadata sent
+
+**Current Approach:** Only transmit essential fields (model ID, security policies) and rely on folder inheritance for other metadata.
+
+---
+
+## Working Example from Postman Collection
+
+The V3 Postman collection includes a "Create Assets and Set Metadata" request with example payload. However:
+
+1. The example uses `import_template_id: 'MARKETING.ASSET'` which returns "No permissable import template found"
+2. The example includes extensive metadata fields
+3. We cannot test this request in Postman as we don't have the Postman environment
+
+---
+
+## Recommended Next Steps
+
+### For Ferrero Support Team:
+
+1. **Verify API upload permissions** for user `scpi.user1` in production environment
+2. **Check file extension whitelist** configuration for `/v6/assets` endpoint
+3. **Provide list of allowed file extensions** for API uploads
+4. **Confirm correct upload endpoint** and required parameters
+5. **Share working example** of successful upload via API (if available)
+
+### For Development Team (Once Resolved):
+
+1. Update AssetUploader with correct endpoint and parameters
+2. Implement proper metadata copying from master assets
+3. Add support for metadata field updates (language, market, etc.)
+4. Test upload workflow end-to-end (A2→A3)
+5. Implement rework upload workflow (A5→A6)
+
+---
+
+## Code Repository
+
+**Bitbucket:** bitbucket.org:zlalani/ferrero-opentext.git
+**Branch:** main
+**Latest Commit:** 0ebdf5c - "Disable master assets fetching in upload"
+
+**Key Files:**
+- `workflow_v3.php` - Main workflow interface
+- `src/AssetUploader.php` - Upload implementation
+- `src/StatusManager.php` - Status updates (working)
+- `config_v3.php` - Configuration
+
+---
+
+## Contact Information
+
+**Developer:** Working through Claude Code
+**Client:** [Your contact information]
+**Issue Tracker:** GitHub Issues (if applicable)
+
+---
+
+## Appendix: Full Error Log
+
+### Sample Upload Request (Simplified)
+
+**URL:**
+```
+POST https://ppr.dam.ferrero.com/otmmapi/v6/assets
+```
+
+**Headers:**
+```
+Accept: application/json
+Authorization: Bearer [valid_oauth_token]
+Content-Type: multipart/form-data; boundary=----WebKitFormBoundary...
+```
+
+**Form Fields:**
+```
+asset_representation: {"asset_resource":{"asset":{"name":"test.jpg","security_policy_list":[{"id":1594}]}}}
+manifest: {"upload_manifest":{"master_files":[{"file":{"file_name":"test.jpg","file_type":"image/jpeg"}}]}}
+parent_folder_id: ea0dbf86e13e3634895746d3a986558ec2eb8be1
+files: [binary file data]
+```
+
+**Response:**
+```json
+{
+  "exception_body": {
+    "http_response_code": 500,
+    "message": "Cannot import asset having restricted file extension.",
+    "debug_message": "Asset creation failed due to restricted file extension",
+    "error_code": 1000
+  }
+}
+```
+
+---
+
+**End of Document**
diff --git a/workflow_v3.php b/workflow_v3.php
index 6ba9977..7f58d56 100644
--- a/workflow_v3.php
+++ b/workflow_v3.php
@@ -263,10 +263,53 @@ if ($_POST && $testRunner) {
 
                     if ($uploadFolderId) {
                         $results['upload_folder_id'] = $uploadFolderId;
-                        $success = "Found upload target folder";
 
-                        // TODO: Master assets fetching disabled - causes PHP crashes due to metadata size
-                        // Will re-enable once upload file extension issue is resolved
+                        // Get Master Assets to copy their metadata
+                        try {
+                            $masterFolderId = findMasterAssetsFolder($testRunner, $campaignId, $configV3);
+                            if ($masterFolderId) {
+                                $fullMasterAssets = getAssetsFromFolder($testRunner, $masterFolderId);
+
+                                // Store lightweight version - only IDs and basic info
+                                $results['master_assets_for_upload'] = [];
+                                if (!empty($fullMasterAssets)) {
+                                    foreach ($fullMasterAssets as $asset) {
+                                        // Only store minimal fields - no huge metadata structure
+                                        $lightAsset = [
+                                            'asset_id' => $asset['asset_id'] ?? null,
+                                            'name' => $asset['name'] ?? 'Unknown',
+                                            'mime_type' => $asset['mime_type'] ?? null
+                                        ];
+
+                                        // Safely extract metadata_model_id if it exists
+                                        if (isset($asset['metadata_model_id'])) {
+                                            $lightAsset['metadata_model_id'] = $asset['metadata_model_id'];
+                                        }
+
+                                        // Safely extract security policy IDs only
+                                        if (isset($asset['security_policy_list']) && is_array($asset['security_policy_list'])) {
+                                            $policyIds = [];
+                                            foreach ($asset['security_policy_list'] as $policy) {
+                                                if (isset($policy['id'])) {
+                                                    $policyIds[] = ['id' => $policy['id']];
+                                                }
+                                            }
+                                            if (!empty($policyIds)) {
+                                                $lightAsset['security_policy_list'] = $policyIds;
+                                            }
+                                        }
+
+                                        $results['master_assets_for_upload'][] = $lightAsset;
+                                    }
+                                }
+
+                                $success = "Found upload folder and " . count($results['master_assets_for_upload']) . " master assets for reference";
+                            } else {
+                                $success = "Found upload target folder (no master assets folder found)";
+                            }
+                        } catch (Exception $e) {
+                            $success = "Found upload target folder (master assets error: " . $e->getMessage() . ")";
+                        }
                     } else {
                         $error = "Upload folder not found in campaign";
                     }