Cannot import installed npm package in Code node (in task runner)

Questions
1

Describe the problem/error/question

After following the instructions on how to install custom npm/Python packages in the docker runner, the JS package cannot actually be used in the Code node.

The instructions are for n8n v1 and I’m running v2. If works for Python, but not for npm packages.

I also opened a ticket here, but it was closed without actually solving it, so I posted it here again.

What is the error message (if any)?

Cannot assign to read only property ‘constructor’ of object ‘Error’

Please share your workflow

The docker compose installs the necessary custom packages, a Puppeteer instance is also needed:

services:
  n8n:
    image: n8nio/n8n
    restart: unless-stopped
    environment:
      - N8N_RUNNERS_MODE=external
      - N8N_BLOCK_ENV_ACCESS_IN_NODE=false # Allow $env in "Code" node.
      - N8N_RUNNERS_BROKER_LISTEN_ADDRESS=0.0.0.0
      - N8N_RUNNERS_AUTH_TOKEN=${N8N_RUNNERS_AUTH_TOKEN}
      - BROWSERLESS_TOKEN=${BROWSERLESS_TOKEN}
    volumes:
      - ./n8n:/home/node/.n8n
    ports:
      - 5678:5678
  n8n-runners:
    build:
      context: .
      dockerfile_inline: |
        FROM n8nio/runners:stable
        USER root
        RUN cd /opt/runners/task-runner-javascript && pnpm add puppeteer-core
        USER runner
    environment:
      - N8N_RUNNERS_TASK_BROKER_URI=http://n8n:5679
      - N8N_RUNNERS_AUTH_TOKEN=${N8N_RUNNERS_AUTH_TOKEN}
      - N8N_RUNNERS_LAUNCHER_LOG_LEVEL=debug
      - N8N_RUNNERS_INSECURE_MODE=true
    volumes:
      - ./n8n-runners/n8n-task-runners.json:/etc/n8n-task-runners.json
    depends_on:
      - n8n
  browserless:
    image: ghcr.io/browserless/chromium
    restart: unless-stopped
    environment:
      - TOKEN=${BROWSERLESS_TOKEN}

The mounted n8n-task-runners.json file contains the following:

{
  "task-runners": [
    {
      "runner-type": "javascript",
      "workdir": "/home/runner",
      "command": "/usr/local/bin/node",
      "args": [
        "--disallow-code-generation-from-strings",
        "--disable-proto=delete",
        "/opt/runners/task-runner-javascript/dist/start.js"
      ],
      "health-check-server-port": "5681",
      "allowed-env": [
        "PATH",
        "GENERIC_TIMEZONE",
        "NODE_OPTIONS",
        "N8N_RUNNERS_AUTO_SHUTDOWN_TIMEOUT",
        "N8N_RUNNERS_TASK_TIMEOUT",
        "N8N_RUNNERS_MAX_CONCURRENCY",
        "N8N_SENTRY_DSN",
        "N8N_VERSION",
        "ENVIRONMENT",
        "DEPLOYMENT_NAME",
        "HOME"
      ],
      "env-overrides": {
        "NODE_FUNCTION_ALLOW_BUILTIN": "*",
        "NODE_FUNCTION_ALLOW_EXTERNAL": "*",
        "N8N_RUNNERS_HEALTH_CHECK_SERVER_HOST": "0.0.0.0"
      }
    },
    {
      "runner-type": "python",
      "workdir": "/home/runner",
      "command": "/opt/runners/task-runner-python/.venv/bin/python",
      "args": [
        "-I",
        "-B",
        "-X",
        "disable_remote_debug",
        "-m",
        "src.main"
      ],
      "health-check-server-port": "5682",
      "allowed-env": [
        "PATH",
        "N8N_RUNNERS_LAUNCHER_LOG_LEVEL",
        "N8N_RUNNERS_AUTO_SHUTDOWN_TIMEOUT",
        "N8N_RUNNERS_TASK_TIMEOUT",
        "N8N_RUNNERS_MAX_CONCURRENCY",
        "N8N_SENTRY_DSN",
        "N8N_VERSION",
        "ENVIRONMENT",
        "DEPLOYMENT_NAME"
      ],
      "env-overrides": {
        "N8N_RUNNERS_STDLIB_ALLOW": "*",
        "N8N_RUNNERS_EXTERNAL_ALLOW": "*"
      }
    }
  ]
}

This is the n8n workflow definition:

Share the output returned by the last node

The error is displayed. Possibly related to an import issue, but not sure.

Information on your n8n setup

  • n8n version: 2.11.2
  • Database (default: SQLite): SQLite
  • n8n EXECUTIONS_PROCESS setting (default: own, main): main
  • Running n8n via (Docker, npm, n8n cloud, desktop app): Docker
  • Operating system: mac OS Tahoe 26.2
2

@Nurgak I see that the team has already picked up the GitHub issue and is working on a fix. Not sure why it was closed, but it is being investigated internally; the team will follow up on that thread once they have an update.

I’d have to note that modules that depend on runtime (like Puppeteer) were disallowed for security purposes. Setting the environment variable mentioned in the original issue should have worked, which is what the team is working on at the moment.

1 Like
3

@Mookie_Lian Thank you for the information. I had the impression that the problem remained unsolved as a solution was given and the ticket was closed. Unfortunately, the solution did not work. It’s good to know that the issue is being looked at.

1 Like
4

@Nugzari , I’m glad to know your issue was addressed.

Please mark the appropriate answer as the solution to help the community and contributors with future searches.

5

The issue has not been solved yet, so I cannot mark it as solved. The issue persists: the puppeteer-core package cannot be imported and used.