# Traefik custom error middleware for HTTP status 502 doesn't work

**URL:** <https://community.traefik.io/t/traefik-custom-error-middleware-for-http-status-502-doesnt-work/13333>\
**Category:** Traefik v2\
**Tags:** docker-swarm, middleware\
**Created:** [February 4, 2022, 7:24am UTC](https://community.traefik.io/t/traefik-custom-error-middleware-for-http-status-502-doesnt-work/13333 "2022-02-04T07:24:09Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![aleksvujic](https://sea2.discourse-cdn.com/flex020/user_avatar/community.traefik.io/aleksvujic/32/4885_2.png) [@aleksvujic](https://community.traefik.io/u/aleksvujic)\
**Post date:** [February 4, 2022, 7:24am UTC](https://community.traefik.io/t/traefik-custom-error-middleware-for-http-status-502-doesnt-work/13333/1 "2022-02-04T07:24:09Z")

</div>

I would like to serve custom error pages for common HTTP error codes. I was following [this tutorial](https://imandrea.me/blog/traefik-custom-404/). For this purpose, I created the following `docker-compose.yml` file to test the functionality. It consists of:

1. `errorPageHandler` which is a nginx server which is able to return static HTML pages (`404.html` and `502.html`).

2. `whoami1` which routes the request to port 80 of `traefik/whoami` image

3. `whoami2` which routes the request to non-existent port 81 of `traefik/whoami` image which results in 502 - Bad Gateway

```auto
version: "3.7"

services:
  errorPageHandler:
    image: "nginx:latest"
    networks:
      - traefik-net
    volumes:
      - "./ErrorPages:/usr/share/nginx/ErrorPages"
      - "./default.conf:/etc/nginx/conf.d/default.conf"
    deploy:
      replicas: 1
      labels:
        # enable Traefik for this service
        - "traefik.enable=true"
        - "traefik.docker.network=traefik-net"

        # router (catches all requests with lowest possible priority)
        - "traefik.http.routers.error-router.rule=HostRegexp(`{catchall:.*}`)"
        - "traefik.http.routers.error-router.priority=1"
        - "traefik.http.routers.error-router.middlewares=error-pages-middleware"

        # middleware
        - "traefik.http.middlewares.error-pages-middleware.errors.status=400-599"
        - "traefik.http.middlewares.error-pages-middleware.errors.service=error-pages-service"
        - "traefik.http.middlewares.error-pages-middleware.errors.query=/{status}.html"

        # service
        - "traefik.http.services.error-pages-service.loadbalancer.server.port=80"
  
  whoami1:
    image: "traefik/whoami"
    networks:
      - traefik-net
    deploy:
      replicas: 1
      labels:
        # enable Traefik for this service
        - "traefik.enable=true"
        - "traefik.docker.network=traefik-net"

        # router
        - "traefik.http.routers.whoami1.rule=HostRegexp(`whoami1.local`)"
        - "traefik.http.routers.whoami1.service=whoami1"
        
        # service
        - "traefik.http.services.whoami1.loadbalancer.server.port=80"
        - "traefik.http.services.whoami1.loadbalancer.server.scheme=http"
        
  whoami2:
    image: "traefik/whoami"
    networks:
      - traefik-net
    deploy:
      replicas: 1
      labels:
        # enable Traefik for this service
        - "traefik.enable=true"
        - "traefik.docker.network=traefik-net"

        # router
        - "traefik.http.routers.whoami2.rule=HostRegexp(`whoami2.local`)"
        - "traefik.http.routers.whoami2.service=whoami2"
        
        # service
        - "traefik.http.services.whoami2.loadbalancer.server.port=81" # purposely wrong port
        - "traefik.http.services.whoami2.loadbalancer.server.scheme=http"

networks:
  traefik-net:
    external: true
    name: traefik-net

```

Folder `ErrorPages` contains two static HTML files, `404.html` and `502.html`. Content of `default.conf` is:

```auto
server {
    listen 80;
    server_name localhost;

    error_page 404 /404.html;
    error_page 502 /502.html;

    location / {
        root /usr/share/nginx/ErrorPages;
        internal;
    }
}

```

I added the following entries to my `hosts` file (`172.15.16.17` is IP of the server where Traefik and all of the mentioned services are deployed) :

```auto
172.15.16.17 error404.local
172.15.16.17 whoami1.local
172.15.16.17 whoami2.local

```

My observations:

1. When I visit `http://error404.local`, Traefik routes the request to nginx and `404.html` is returned. This is expected behavior because `http://error404.local` doesn't match any of the routes defined in Traefik.

2. When I visit `http://whoami1.local`, Traefik routes request to `whoami1` service and information about container is displayed on the page (expected behavior).

3. When I visit `http://whoami2.local`, Traefik doesn't route request to nginx service, but it displays its default `Bad Gateway` page. Why doesn't it route the request to the nginx?