@Jannik Johann
OT: Check your gmail account as I followed up to your recent contact.
The error message indicates that the App Center Builder has identified an image file with a name that is incompatible for android applications. Android is very tempermental about file names such as images and .mobi files. It is best to use very simple file names that start with Alpha chars and do not contain whitespace or any special chars.
From your message you indicate that have revised references to this image.
1) Please check that an image with the name “2PRODUCT – Test.png” is no longer being directly referenced by your UI design that is being built into an application. That is, look through all of your image widgets for such a reference.
2) If you have no references to this file in your UI design any where please check that the image “2PRODUCT – Test.png” is being referenced (checked) on the Files/Dirs page of the Android App Build Wizard. If it is please uncheck the file and see if you can continue the android app build process.
Please let us know if this resolves the problem or not?