I recently uploaded the new version of WordPress 3.5, and I noticed that the media uploader isn't working correctly.
Indeed, when I want to upload an image in the media uploader, it automatically says that there is an error. Also, when I want to insert in my article an image already in my media library, nothing appears in the media library ! But, when I close my article and I go directly to the library, all seems fine.
I also disabled all my plugins, and fount out it is my Magic fields plugin which is incompatible with the new WordPress version ! And it is really problematic, because my PHP code mainly depends on Magic Fields ...