Add-on Store is broken 'Failed to fetch add-on info'

I’m not using ResinOS, maybe your solution / path is different!
You must have ssh access to your systems root account (not hassio docker)!

  1. Find the missing repository.yaml . In my case, the esphome one was missing as well.
    ls /usr/share/hassio/addons/git
    Folders with numbers were listed. I tried both folders and looked for the one containing esphome.
    cd /usr/share/hassio/addons/git/NUMBER
    The full path in my case is:
    /usr/share/hassio/addons/git/7bce6681/repository.json
  2. Once you are inside the right folder type
    sudo nano repository.json
    and copy paste the following code. (In damiens code is a slight failure in the path)

{
“name”: “ESPhome”,
“url”: “https://github.com/esphome/esphome”,
“maintainer”: “Ottowinter”
}

Hit CTRL + X and save.
3. Reboot System (whole system, not only hassio)

Attention: In my first attempt i was not successful. Somehow the file disappeared after reboot. So i copied over the repository.json from the other repository, just to make sure i got the rights correct. I replaced only the strings, not the entire block. Another reboot later everything was working agan.