The plain HTTP request was sent to HTTPS port: error behind corporate proxy

Questions
1

Describe the problem/error/question

I’m running n8n via docker behind a corporate proxy which does not require authentication. I use the the following command to start n8n:

docker run -it --rm -d \
  --add-host=host.docker.internal:host-gateway \
  -e HTTP_PROXY=http://PROXY_IP:PORT \
  -e HTTPS_PROXY=http://PROXY_IP:PORT \
  -e NO_PROXY=localhost,127.0.0.1,host.docker.internal \
  -e N8N_ENFORCE_SETTINGS_FILE_PERMISSIONS=true \
  -e N8N_RUNNERS_ENABLED=true \
  -e N8N_PROXY_HOPS=1 \
  -e WEBHOOK_URL=http://PROXY_IP:PORT \
  -v n8n_data:/home/node/.n8n \
  -v /home/user/n8n:/my-n8n-data \
  -p 5678:5678 \
  --name n8n \
  docker.n8n.io/n8nio/n8n

What is the error message (if any)?

The API calls to OpenAI fail and when I run a simple http_request I get the following error (The plain HTTP request was sent to HTTPS port):

Error code
400

Full message
400 - "<html>\r\n<head><title>400 The plain HTTP request was sent to HTTPS port</title></head>\r\n<body>\r\n<center><h1>400 Bad Request</h1></center>\r\n<center>The plain HTTP request was sent to HTTPS port</center>\r\n</body>\r\n</html>\r\n"

Request
{ "headers": { "accept": "application/json,text/html,application/xhtml+xml,application/xml,text/*;q=0.9, image/*;q=0.8, */*;q=0.7" }, "method": "POST", "uri": "https://httpbin.org/ip", "gzip": true, "rejectUnauthorized": true, "followRedirect": true, "resolveWithFullResponse": true, "followAllRedirects": true, "proxy": "PROXY_IP:PORT", "timeout": 300000, "encoding": null, "json": false, "useStream": true }

Information on your n8n setup

  • **n8n version: [details=“instance information”]

Debug info

core

  • n8nVersion: 1.86.1
  • platform: docker (self-hosted)
  • nodeJsVersion: 20.19.0
  • database: sqlite
  • executionMode: regular
  • concurrency: -1
  • license: community
  • consumerId: unknown

storage

  • success: all
  • error: all
  • progress: false
  • manual: true
  • binaryMode: memory

pruning

  • enabled: true
  • maxAge: 336 hours
  • maxCount: 10000 executions

client

  • userAgent: mozilla/5.0 (x11; linux x86_64) applewebkit/537.36 (khtml, like gecko) chrome/128.0.0.0 safari/537.36 edg/128.0.0.0
  • isTouchDevice: false

Generated at: 2025-04-10T17:08:18.586Z**
[/details]

  • Database (default: SQLite): default
  • Running n8n via: Docker version 28.0.4, build b8034c0
  • Operating system: Ubuntu 24.04.2
2

axios (which n8n uses for web requests) uses the HTTPS_PROXY and/or HTTP_PROXY env variables according to its readme.

According to this it might be worth checking to see if the PORT that you are setting in -e HTTP_PROXY=http://PROXY_IP:PORT is explicitly set to 80. If so, try leaving the port off and letting it use the default http port (which is still port 80) with just -e HTTP_PROXY=http://PROXY_IP

3

Thank you. I tried that and I got the following error:

{
  "errorMessage": "The service refused the connection - perhaps it is offline",
  "errorDetails": {
    "rawErrorMessage": [
      "connect ECONNREFUSED PROXY_IP:80",
      "connect ECONNREFUSED PROXY_IP:80"
    ],
    "httpCode": "ECONNREFUSED"
  },
  "n8nDetails": {
    "nodeName": "HTTP Request1",
    "nodeType": "n8n-nodes-base.httpRequest",
    "nodeVersion": 4.2,
    "itemIndex": 0,
    "time": "11/04/2025, 10:28:30",
    "n8nVersion": "1.86.1 (Self Hosted)",
    "binaryDataMode": "default",
    "stackTrace": [
      "NodeApiError: The service refused the connection - perhaps it is offline",
      "    at ExecuteContext.requestWithAuthentication (/usr/local/lib/node_modules/n8n/node_modules/n8n-core/dist/execution-engine/node-execution-context/utils/request-helper-functions.js:991:19)",
      "    at processTicksAndRejections (node:internal/process/task_queues:95:5)",
      "    at ExecuteContext.requestWithAuthentication (/usr/local/lib/node_modules/n8n/node_modules/n8n-core/dist/execution-engine/node-execution-context/utils/request-helper-functions.js:1147:20)"
    ]
  }
}

As an additional info, this happens with the OpenAI interface. I’m using for example a Google Mail component to send out some automated emails in my workflow and the connection to my Google API works fine.

4

Just to make sure: You did change PROXY_IP to the actual proxy IP :wink:

5

Of course :slight_smile: My company also uses a socks5 proxy which has solved some connectivity issues in other applications in the past, but I’m not sure if this is supported in n8n? It’s the same IP with a different port.

6

There is an open feature request for socks5 proxy support that mentions openai specifically. I didn’t see anything that would help you but it might be worth up-voting, and it might confirm your suspicions about what isn’t working.

7

Any solution? I’m facing exactly the same issue