Site moved but media uploader not working

I move the site to subfolder and I believe I have done all the steps to correct paths etc. wp-config and database. However when I try to upload images, media uploader just says “crunching” and stays stuck there. When looking with FTP, the image is just fine in correct folder and in database image has reference in wp_posts table. When leaving the mediauploader and returning back, there is broken icon in media list and I cannot manipulate it.

I think something has changed more in 3.6 etc. due I was able to move couple sites last year in similar fashion without issues. Is there a way to debug?