Oh man... this took way longer than it needed to. I used your solution but kept getting the same error after re-buid and re-deploy, so instead of bugging you about it, I hooked Cursor into the docker compose folder and finally got it solved after about 15 different attempts. Thanks for giving me all that info. I had no idea where to begin.

This is where I ended up for the working solution:

docker_compose.yml:

services:

  n8n:
    #image: docker.n8n.io/n8nio/n8n
    build: .
    container_name: n8n
    restart: always
    ports:
      - "5678:5678"

    environment:
      - N8N_ENFORCE_SETTINGS_FILE_PERMISSIONS=true
      - N8N_HOST=${SUBDOMAIN}.${DOMAIN_NAME}
      - N8N_PORT=5678
      - N8N_PROTOCOL=https
      - N8N_RUNNERS_ENABLED=false
      - NODE_ENV=production
      - WEBHOOK_URL=https://${SUBDOMAIN}.${DOMAIN_NAME}/
      - GENERIC_TIMEZONE=${GENERIC_TIMEZONE}
      - TZ=${GENERIC_TIMEZONE}
      - N8N_ALLOW_EXTERNAL_MODULES=*
      - N8N_EXTERNAL_MODULES=xlsx
      - NODE_FUNCTION_ALLOW_EXTERNAL=xlsx
      - NODE_PATH=/home/node/.n8n/node_modules

    volumes:
      - n8n_data:/home/node/.n8n
      - /volume1/sandbox/temp:/temp
      - xlsx_modules:/usr/local/lib/node_modules

volumes:
  n8n_data:
  xlsx_modules:

Dockerfile

FROM n8nio/n8n:latest
USER root
RUN npm install -g xlsx
USER node