I already know why it does this. There are 2 reasons that I know of.
1) you uploaded a type that isn't supported. This is funny though, as jpeg = jpg, but the website doesn't like jpeg so just rename the file to .jpg
2) I think there is a 2MB file limit. It is around there somewhere. If the image is to big it gives that error.
yes, the error messages are really stupid as they don't help at all 








