# Common sources of error 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: Finally, reinstall the app again. After that everything should work as far as possible. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.shop-studio.io/shopware/extensions/tree-per-order/common-sources-of-error.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.