fix: n8n 2.0 compatibility - binary data access and Accept headers

[Deepak-Kesavan]

🐛 Problem

n8n 2.0 introduced breaking changes that caused errors in our custom nodes:

• ❌ HTTP 406 errors in Unstract nodes
• ❌ UTF-8 encoding errors in LLMWhisperer
• ❌ Binary file uploads failing

🔧 Root Causes

1. Binary Data Access Changed

In n8n 2.0, binary data is no longer stored in-memory. The old approach of accessing binaryData.data and converting from base64 is deprecated.

Before (❌ Broken):

const binaryData = items[i].binary![fileContents];
const fileBuffer = Buffer.from(binaryData.data, 'base64');

After (✅ Fixed):

const fileBuffer = await this.helpers.getBinaryDataBuffer(i, fileContents);

2. Accept Header Auto-Generation

n8n 2.0 automatically adds Accept: application/json,text/*;q=0.99 which some APIs reject. Unstract/LLMWhisperer APIs require exactly Accept: application/json.

Fix: Explicitly set Accept: application/json in headers to override the default.

✅ Changes Made

Binary Data Access (3 nodes)

• LlmWhisperer.node.ts - Updated to use getBinaryDataBuffer()
• Unstract.node.ts - Updated to use getBinaryDataBuffer()
• UnstractHitlPush.node.ts - Updated to use getBinaryDataBuffer()

Accept Headers (8 locations)

• LLMWhisperer: POST request + status check + retrieve request
• Unstract: POST request + status check
• UnstractHitlFetch: GET request
• UnstractHitlPush: POST request + status check

🧪 Testing

✅ Tested on n8n 2.0
✅ All nodes successfully process binary file uploads
✅ No HTTP 406 errors
✅ No UTF-8 encoding errors

📚 References

• n8n 2.0 Breaking Changes
• Binary Data in n8n 2.0
• Get Binary Data Buffer

📝 Files Changed

• nodes/LlmWhisperer/LlmWhisperer.node.ts
• nodes/Unstract/Unstract.node.ts
• nodes/UnstractHitlFetch/UnstractHitlFetch.node.ts
• nodes/UnstractHitlPush/UnstractHitlPush.node.ts