A TimThumb error has occured

The following error(s) occured:

The remote file is not a valid image. Mimetype = 'text/html' File = /var/www/html/timthumb/cache/timthumb2gywkb

Query String : w=210&h=180&zc=1&a=c&src=http://glamping.it/uploads/image/1498549594515.jpg
TimThumb version : 2.8.13