This is not an error message, there's nothing wrong with ISO if and when this is shown:
It is a system notification, a warning to you when Windows setup detects an existing Windows installation on the machine which you have just booted up with install media.
Reading it carefully it tells you quite clearly what it is about. If you do not want to wipe your existing Windows installation, remove the install media (DVD or USB) and click Yes to restart. You can then do the upgrade starting Windows setup from desktop instead of booting with install media. If you really want to clean install Windows now, wiping the existing installation, click No.
Short answer: nothing is going on. That notification is there to protect you, a kind of "Are you sure you want to clean install now?" question.