See when you go to the 'Edit' don't upload any new photo. Just check the box 'Delete Image' and after that save the changes. Now again upload your photo and it should be uploaded with no Errors. After that logout of QL, login again and you should see your new Avatar.
I did this yesterday and shifted from Danty [Devil May Cry] to Metallica [Master Of Puppets] :)

Best Regards