A TimThumb error has occured

The following error(s) occured:

The remote file is not a valid image. Mimetype = ''/home/user06579/anyzovafotografie.cz/www/wp-content/plugins/photoblocks-grid-gallery/public/cache/timthumbINzjLx

Query String : zc=4&max=1600&src=http://www.anyzovafotografie.cz/wp-content/uploads/2020/04/11-683x1024.jpg
TimThumb version : PhotoBlocks