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/timthumbxp3yrW

Query String : w=1900&h=670&zc=1&a=c&q=70&src=https://www.glamping.it/uploads/image/1406644727477.jpg
TimThumb version : 2.8.13