# Common sources of errors

APP\_URL is wrong in the .env

On the server there is an .env file where an important URL is stored at the variable APP\_URL. This URL is used so that the external app contains a URL from your Shopware store for communication back (this is an external Shopware cloud app). 

Unfortunately, this URL is almost always set incorrectly for self-hosted stores - already by the installer. The URL could be similarly wrong as here:

```
APP_URL="http://127.0.0.1"
```

It is important to use the URL of the store for the correction. It is also important to note http & https. In some cases, it can also be a different URL to the admin of the store (eg Shopware PWA or multiple store domains within one installation). Correct would be e.g.

```
APP_URL="https://www.my-shop.com"
```

After the change, save the file once and clear the store cache. Now a new window will appear in the admin because the URL has changed. Here would be a way to tell all external cloud apps that the URL has changed because the store has "moved". There is a little more at this point: <https://developer.shopware.com/docs/guides/plugins/apps/app-base-guide#handling-the-migration-of-shops>

Finally, reinstall the app again. After that everything should work as far as possible.