Photo Upload not working – photos black

Recently the photo upload is not working anymore, I dont get any error information. I can upload a photo and everything seems correct, except the photo only shows a black square. If I use it on my site, it’s the same, so the photos apperently dont upload. I have no idea what to do now, when I googled it, it seemed that there has to be a concrete error message, I didnt find anything for this case. I deleted other photos, so it cant be to little memory space. I turnd off plugins, also nothing happend.
Recently I followed the recommendation to update word press version and plugins, can this cause the error?
Can anyone help me please?

The page I need help with: [log in to see the link]