404 - URL not provided in the app Scully is serving

The url "/blog/eiwei%C3%9F-einfach-erklaert" is not provided in the scully.routes.json, so it can't be generated

If you have routes that are not known before you might want to serve index.html instead of this response.
That can be done by adding the '--404=index' option to the Scully command