Shopware 6 cloud app fails to connect with the server during installation/registration request

Shopware Cloud
1

Problem

Am learning the Shopware 6 app system using the official documentation. The app installs successfully when there is no setup in the manifest.xml file to register with a back-end server, but when I include a setup to the manifest.xml the App installation process fails with the following error:

[GuzzleHttp\Exception\ClientException (404)]                                                                                                                                                 
  Client error: `GET http://localhost:8000/register?shop-id=VQA0QLjSSO0y94lD&shop-url=http://shopware6demo.web-env.de&timestamp=1663100075` resulted in a `404 Not Found` response:  
  <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">                                                                                                                                           
  <html><head>                                                                                                                                                                                 
  <title>404 Not Found</title>                                                                                                                                                                 
  </head><body>                                                                                                                                                                                
  <h1>Not Found (truncated...)

Now, when I visit the same URL with a browser or Postman I get Signature is not present in request, which makes sense because shopware-app-signature is not set, but It also proves that my URL works.

My Setup:

  • Shopware v6.4.14 instance running on http://shopware6demo.web-env.de.
  • App Template available on http://localhost:8000.
manifest.xml
<?xml version="1.0" encoding="UTF-8"?>
<manifest xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/shopware/platform/trunk/src/Core/Framework/App/Manifest/Schema/manifest-1.0.xsd">
    <meta>
        <!-- Meta content -->
    </meta>

    <setup>
        <registrationUrl>http://localhost:8000/register</registrationUrl>
        <secret>random-secret</secret>
    </setup>
</manifest>

Currently my app only contains a manifest.xml file and a Resources/config/plugin.png, nothing more.

Question

What am I doing wrong? Or should I say „What is Shopware omitting in the documentation?“.

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