Re: Re: Image error "File is not an image." TW9.2
For what it is worth, I have the same problem. I can upload a zip file in the gallery, but I get that error message and it can't display it.
I can circumvent this by editing the page as wiki text and then replacing "img" with "file"
That fixes it, so it seems to me that the file gallery is broken, doesn't detect the mime type even though the server does.
I'm using 11.1