I was posting an idea on CVI idea exchange board and was continuously getting a generic error ("Codice di errore: caricamento non riuscito" which means "error code: unsuccessful loading") while trying to add an image.
After several studies and attempts I realized that the problem is not in the image size or name or whatsoever element but rather in the color depth: it arises with 32-bit images, while you can post 24-bit images without problems. This applies to other forum boards as well (just tested on CVI board and this actual message), I suppose it is a general rule.
I don't seem to have noted any note on this in the forum help: there exists some documentation on which objects the forums accept as attachments? You know: file types, image types and characteristics, object sizes and so on...