Bug Description

The HTTP Request node throws NodeApiError: config.headers.setContentType is not a function when the request URL starts with https://api.openai.com/. The error originates inside the global axios request interceptor in packages/core/src/execution-engine/node-execution-context/utils/request-helpers/axios-config.ts at line 30:

  if (config.data === undefined) {
      config.headers.setContentType(false, false);
  }

The interceptor assumes config.headers is an AxiosHeaders instance, but applyVendorHeaders (lines 39–46 in the same file) reassigns config.headers to a plain object literal whenever the URL targets OpenAI:

  config.headers = {
      ...Container.get(AiConfig).openAiDefaultHeaders,
      ...(config.headers ?? {}),
  };

Plain objects don't expose setContentType, so any downstream invocation of the interceptor on that mutated config (including the path triggered by the V3 HTTP Request node when sending no body) raises the TypeError, which is caught and rewrapped as NodeApiError at HttpRequestV3.node.js:588.

To Reproduce

1. Create a workflow with an HTTP Request node (typeVersion 4.2).
2. Set: - Method: GET - URL: https://api.openai.com/v1/models - Authentication: None - Send Headers: true, with Authorization: Bearer <key> and OpenAI-Organization: <org> (I think this second header may be optional for reproducibility).
3. Execute the workflow.
4. The node fails with NodeApiError: config.headers.setContentType is not a function.

A minimal workflow JSON that reproduces the issue (single "Get models" node hitting https://api.openai.com/v1/models) is enough; no credentials are required because the failure happens before the request leaves the instance.

Expected behavior

The HTTP Request node should successfully reach https://api.openai.com/v1/models (or whichever OpenAI endpoint), receive the response from OpenAI, and surface it as the node output. The interceptor should not throw, regardless of whether applyVendorHeaders rewrites the headers as a plain object or an AxiosHeaders instance.

Debug Info

Debug info

core

• n8nVersion: 2.19.0
• platform: docker (self-hosted)
• nodeJsVersion: 22.21.0
• nodeEnv: production
• database: postgres
• executionMode: scaling (single-main)
• concurrency: 60

storage

• success: all
• error: all
• progress: false
• manual: false
• binaryMode: filesystem

pruning

• enabled: true
• maxAge: 336 hours
• maxCount: 5000 executions

security

• blockFileAccessToN8nFiles: false

Generated at: 2026-04-29T10:07:45.227Z

Operating System

N/A

n8n Version

2.19.0

Node.js Version

22.21.0

Database

PostgreSQL

Execution mode

queue

Hosting

self hosted