Why does my n8n instance show ERR_SSL_PROTOCOL_ERROR behind Traefik with Let’s Encrypt?

Hello n8n community,

I’m facing an SSL issue when accessing my n8n instance through a Traefik reverse proxy. When I navigate to https://n8n.jmcruz.me, my browser reports:
"This site can’t provide a secure connection
n8n.jmcruz.me sent an invalid response.
ERR_SSL_PROTOCOL_ERROR"

My setup includes:

• n8n and Traefik running in Docker containers
• PostgreSQL as the database (running in a separate container)
• Ubuntu VPS
• Domain: n8n.jmcruz.me

I’ve configured Traefik to utilize Let’s Encrypt for SSL certificates. Below is my docker-compose.yml file:

YAMLCopied
version: '3'

services:
  traefik:
    image: "traefik"
    restart: always
    command:
      - "--api=true"
      - "--api.insecure=true"
      - "--providers.docker=true"
      - "--providers.docker.exposedbydefault=false"
      - "--entrypoints.web.address=:80"
      - "--entrypoints.web.http.redirections.entryPoint.to=websecure"
      - "--entrypoints.web.http.redirections.entrypoint.scheme=https"
      - "--entrypoints.websecure.address=:443"
      - "--certificatesresolvers.mytlschallenge.acme.tlschallenge=true"
      - "--certificatesresolvers.mytlschallenge.acme.email=${SSL_EMAIL}"
      - "--certificatesresolvers.mytlschallenge.acme.storage=/letsencrypt/acme.$"
      # ... other options ...
       - "--serversTransport.forwardingTimeouts.dialTimeout=30s"
      - "--serversTransport.forwardingTimeouts.responseHeaderTimeout=30s"
      - "--log.level=DEBUG"
      - "--accesslog=true"
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - /n8n/letsencrypt:/letsencrypt
      - /var/run/docker.sock:/var/run/docker.sock:ro

  n8n:
    image: n8nio/n8n
    container_name: n8n
    restart: always
    ports:
      - "5678:5678"
    environment:
      - DB_TYPE=postgresdb
      - DB_POSTGRESDB_HOST=n8n-postgres
      - DB_POSTGRESDB_PORT=5432
      - DB_POSTGRESDB_DATABASE=n8n
      - DB_POSTGRESDB_USER=n8n
      - DB_POSTGRESDB_PASSWORD=n8npassword
      - NODE_ENV=production
      - WEBHOOK_URL=https://${SUBDOMAIN}.${DOMAIN_NAME}/
      - GENERIC_TIMEZONE=${GENERIC_TIMEZONE}
      - N8N_LOG_LEVEL=debug
    volumes:
      - ~/n8n-data:/home/node/.n8n
    networks:
      - n8n-network
    labels:
      - traefik.enable=true
      - traefik.http.routers.n8n.rule=Host(`${SUBDOMAIN}.${DOMAIN_NAME}`)
      - traefik.http.routers.n8n.tls=true
      - traefik.http.routers.n8n.entrypoints=web,websecure
      - traefik.http.routers.n8n.tls.certresolver=mytlschallenge
      - traefik.http.middlewares.n8n.headers.SSLRedirect=true
      - traefik.http.middlewares.n8n.headers.STSSeconds=315360000
      - traefik.http.middlewares.n8n.headers.browserXSSFilter=true
      - traefik.http.middlewares.n8n.headers.contentTypeNosniff=true
      - traefik.http.middlewares.n8n.headers.forceSTSHeader=true
      - traefik.http.middlewares.n8n.headers.SSLHost=${DOMAIN_NAME}
      - traefik.http.middlewares.n8n.headers.STSIncludeSubdomains=true
      - traefik.http.middlewares.n8n.headers.STSPreload=true
      - traefik.http.routers.n8n.middlewares=n8n@docker

networks:
  n8n-network:
    external: true

volumes:
  traefik_data:

I’ve attempted the following troubleshooting steps:

1. Set Traefik log level to DEBUG
2. Set n8n log level to debug
3. Verified ports 80 and 443 are open
4. Confirmed DNS settings for n8n.jmcruz.me
5. Restarted the containers multiple times

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Despite these efforts, I still cannot access the n8n editor due to the SSL error. Traefik logs don’t reveal any apparent issues with certificate acquisition. Can anyone help identify the cause of this SSL error or suggest additional troubleshooting steps?

Note:
I previously had a working n8n server for about a month until I switched to PostgreSQL, at which point this problem began. I followed the instructions here: n8n - Docker Compose Installation.

I’m still learning about server management, so apologies if this seems like a beginner question. I’ve been troubleshooting for the past two days with help from this forum and AI, and I’m starting to feel overwhelmed. Any guidance would be appreciated. Thank you in advance for your help!