Short and final update on this - I give up.
Reimaged the card, edited the .env file before first start, so directly pulled the fat image. Set up my standard Modules, everything up and running - except MMM-FRITZ-BoxCallmonitor - and started to test mounts to map the fritzconnection Python scripts… as again, a strange container showed up:

pi@magicmirroros:/opt/mm/run $ docker compose up -d
WARN[0000] No services to build                         
[+] up 2/2
 ✘ Container b053acabeef9 Error response from daemon: No such container: b053acabeef9f142eb3382656732bee6b75d549c10ec2ef80da27ec2c60946d6                                          2.2s 
 ✔ Container labwc        Recreated                                                                                                                                                2.2s 
Error response from daemon: No such container: b053acabeef9f142eb3382656732bee6b75d549c10ec2ef80da27ec2c60946d6

Now I am sure my trusty SDcard is corrupt. Thanks @karsten13 for all the troubleshooting and help! I have learned a lot around Docker last days.

Will get a new card and see some time. Other projects requiring my attention.

@karsten13

To make it short - same. Will start from scratch and let you know.

@karsten13

After docker compose down, prune resulted in Total reclaimed space: 0B .

When trying to start the containers and running the commands:

pi@magicmirrorMB:/opt/mm/run $ docker compose up -d
WARN[0000] No services to build                         
[+] up 2/2
 ✔ Network magicmirror_default Created                                                                               0.2s 
 ✔ Container mm                Created                                                                               0.5s 
Error response from daemon: No such container: 1b169eacdb711404e12c838a79de243c677daaaea260867d04c133a86cc3025b
pi@magicmirrorMB:/opt/mm/run $ docker system prune -f
Deleted Containers:
b04e79ead19ae7e42b7c7899f8e9b4b2d4f870770362c684bfadbfdaae6725aa

Deleted Networks:
magicmirror_default

Total reclaimed space: 4.096kB
pi@magicmirrorMB:/opt/mm/run $ docker ps -a
CONTAINER ID   IMAGE                    COMMAND            CREATED      STATUS                    PORTS     NAMES
1b169eacdb71   karsten13/labwc:latest   "/entrypoint.sh"   9 days ago   Exited (128) 2 days ago             

I think the easiest way is to start from scratch. Save the config.js, remember the modules and just reinstall. Switch to fat image again and fiddle around with FRITZ stuff. Sorry for keeping you busy and thanks a lot for your help and patience!

Let me know if you want to finish troubleshooting ;-)

@karsten13
Is there a way to reload the images from scratch, delete them from the RPi without losing the customization?

@karsten13

pi@magicmirrorMB:/opt/mm/run $ docker ps -a
CONTAINER ID   IMAGE                    COMMAND            CREATED      STATUS                    PORTS     NAMES
1b169eacdb71   karsten13/labwc:latest   "/entrypoint.sh"   8 days ago   Exited (128) 2 days ago             
pi@magicmirrorMB:/opt/mm/run $ 

What? There must be something completely wrong…

@karsten13
Doesn´t look good. I’m too noob about Docker to really understand what’s going on:

pi@magicmirrorMB:~ $ cd /opt/mm/run/
pi@magicmirrorMB:/opt/mm/run $ docker compose down
[+] down 1/1
 ✔ Container 1b169eacdb71 Removed                                          0.0s 
pi@magicmirrorMB:/opt/mm/run $ docker rm -f $(docker ps -aq)
Error response from daemon: No such container: 1b169eacdb71
pi@magicmirrorMB:/opt/mm/run $ docker compose up -d
WARN[0000] No services to build                         
[+] up 2/2
 ✔ Network magicmirror_default Created                                     0.2s 
 ✔ Container mm                Created                                     0.9s 

After last line just nothing happens. No prompt, no display on mirror.
Can I check where the strange container is called or where the reference is?

@karsten13
Sorry for being that unspecific. I changed the .env file in the “Docker image to use” section:

# Docker Images to use:
MM_IMAGE="karsten13/magicmirror:v2.34.0_fat"
LABWC_IMAGE="karsten13/labwc:latest"
MMPM_IMAGE="karsten13/mmpm:latest"
WATCHTOWER_IMAGE="ghcr.io/nicholas-fedor/watchtower:latest"

Executed cd /opt/mm/run && docker compose up -d --force-recreate and the download started. After successfully pulling the image, Terminal stopped here:

 ✔ Image karsten13/magicmirror:fat Pulled                                318.2s 
   ✔ 304150113e8d                  Pull complete                          97.1s 
   ✔ 964f5c44c7bd                  Pull complete                           0.9s 
   ✔ ac8996972af0                  Pull complete                           0.9s 
   ✔ 3ee9d8e5c8b3                  Pull complete                         131.8s 
   ✔ f9b5315e0a0e                  Pull complete                           0.8s 
   ✔ 5e7a4985a616                  Pull complete                           0.7s 
   ✔ 9f175b8c171e                  Pull complete                          98.7s 
   ✔ c1be2df81e57                  Pull complete                           0.7s 
   ✔ 4f4fb700ef54                  Pull complete                           0.0s 
   ✔ 9dcfcb600955                  Pull complete                           1.0s 
   ✔ 0902543587b7                  Pull complete                         212.6s 
   ✔ 6454a8f98e11                  Pull complete                         314.9s 
   ✔ fe8e38a18048                  Pull complete                          97.6s 
   ✔ a4662295f62c                  Pull complete                           0.9s 
   ✔ c5dcf86b0f8a                  Pull complete                           1.0s 
 ✔ Network magicmirror_default     Created                                 0.4s 
 ✘ Container 1b169eacdb71          Error response from daemon: No such container: 1b169eacdb711404e12c838a79de243c677daaaea260867d04c133a86cc3025b 6.8s 

Output of docker compose config:

name: magicmirror
services:
  labwc:
    container_name: labwc
    environment:
      LAB_WC_HIDE_CURSOR: "true"
      RANDR_PARAMS: ""
      RANDR_POLL: 1m
      XDG_RUNTIME_DIR: /tmp/labwc
    image: karsten13/labwc:latest
    networks:
      default: null
    privileged: true
    restart: always
    volumes:
      - type: bind
        source: /tmp/labwc
        target: /tmp/labwc
        bind: {}
      - type: bind
        source: /run/udev
        target: /run/udev
        bind: {}
  magicmirror:
    container_name: mm
    depends_on:
      labwc:
        condition: service_healthy
        restart: true
        required: true
    environment:
      DISPLAY: unix:0.0
      ELECTRON_ENABLE_GPU: "0"
      MM_CUSTOMCSS_FILE: css/custom.css
      MM_MODULES_DIR: modules
      MM_OVERRIDE_DEFAULT_MODULES: "true"
      MM_SCENARIO: electron
      MM_SHOW_CURSOR: "false"
      WAYLAND_DISPLAY: wayland-0
      XDG_RUNTIME_DIR: /tmp/labwc
    image: karsten13/magicmirror:v2.34.0_fat
    network_mode: host
    privileged: true
    restart: always
    shm_size: "268435456"
    volumes:
      - type: bind
        source: /tmp/.X11-unix
        target: /tmp/.X11-unix
        bind: {}
      - type: bind
        source: /home/pi/.Xauthority
        target: /home/node/.Xauthority
        bind: {}
      - type: bind
        source: /tmp/labwc
        target: /tmp/labwc
        bind: {}
      - type: bind
        source: /opt/mm/mounts/config
        target: /opt/magic_mirror/config
        bind: {}
      - type: bind
        source: /opt/mm/mounts/modules
        target: /opt/magic_mirror/modules
        bind: {}
      - type: bind
        source: /opt/mm/mounts/css/custom.css
        target: /opt/magic_mirror/css/custom.css
        bind: {}
    post_start:
      - command:
          - /bin/sh
          - -c
          - |
            if [ "init" = "init" ]; then
              # update volume permissions
              chown -R 1000:1000 config modules css/custom.css
              chmod -R 777 config modules css/custom.css
            fi
            if command -v node_modules/.bin/electron > /dev/null; then
              # if electron is installed then start dbus-daemon to avoid errors in the logs
              dbus-daemon --system || true
            fi
        user: root
networks:
  default:
    name: magicmirror_default

Hello @karsten13,
I have changed the docker image to fat in .env file. Unfortunately, after pulling the docker image, the script stopped with error: No such container: 1b169eacdb711[~35 more numbers/letters].
Magic Mirror stopped working :( What did I do wrong?

Pi rebooted twice today (initiated by myself) and issue didn’t come back - I think this can bei marked as resolved - thanks a lot!

Now I can take care about Python and fritzconnector…

@karsten13
Back to function! Several restarts without blank screen!

Output of docker compose config - in case it is useful…

name: magicmirror
services:
  labwc:
    container_name: labwc
    environment:
      LAB_WC_HIDE_CURSOR: "true"
      RANDR_PARAMS: ""
      RANDR_POLL: 1m
      XDG_RUNTIME_DIR: /tmp/labwc
    image: karsten13/labwc:latest
    networks:
      default: null
    privileged: true
    restart: always
    volumes:
      - type: bind
        source: /tmp/labwc
        target: /tmp/labwc
        bind: {}
      - type: bind
        source: /run/udev
        target: /run/udev
        bind: {}
  magicmirror:
    container_name: mm
    depends_on:
      labwc:
        condition: service_healthy
        restart: true
        required: true
    environment:
      DISPLAY: unix:0.0
      ELECTRON_ENABLE_GPU: "0"
      MM_CUSTOMCSS_FILE: css/custom.css
      MM_MODULES_DIR: modules
      MM_OVERRIDE_DEFAULT_MODULES: "true"
      MM_SCENARIO: electron
      MM_SHOW_CURSOR: "false"
      WAYLAND_DISPLAY: wayland-0
      XDG_RUNTIME_DIR: /tmp/labwc
    image: karsten13/magicmirror:latest
    network_mode: host
    privileged: true
    restart: always
    shm_size: "268435456"
    volumes:
      - type: bind
        source: /tmp/.X11-unix
        target: /tmp/.X11-unix
        bind: {}
      - type: bind
        source: /home/pi/.Xauthority
        target: /home/node/.Xauthority
        bind: {}
      - type: bind
        source: /tmp/labwc
        target: /tmp/labwc
        bind: {}
      - type: bind
        source: /opt/mm/mounts/config
        target: /opt/magic_mirror/config
        bind: {}
      - type: bind
        source: /opt/mm/mounts/modules
        target: /opt/magic_mirror/modules
        bind: {}
      - type: bind
        source: /opt/mm/mounts/css/custom.css
        target: /opt/magic_mirror/css/custom.css
        bind: {}
    post_start:
      - command:
          - /bin/sh
          - -c
          - |
            if [ "init" = "init" ]; then
              # update volume permissions
              chown -R 1000:1000 config modules css/custom.css
              chmod -R 777 config modules css/custom.css
            fi
            if command -v node_modules/.bin/electron > /dev/null; then
              # if electron is installed then start dbus-daemon to avoid errors in the logs
              dbus-daemon --system || true
            fi
        user: root
networks:
  default:
    name: magicmirror_default