How to find the error in QNetworkReply?

[ChrisW67]

To further emphasise: there is a difference between a URL and a file. Many URLs ultimately map directly to a file, but they may redirect elsewhere, be summarily ignored (e.g. if no session cookie present), or a response can be generated on the fly. In this case the server has converted the target path "/topic/123.gif" to a redirect (which it tells you about with status code 302), and the target of the redirection is an HTML document that tells a human viewer that the requested URL does not exist (which does exist resulting in a 200 status code).