A TimThumb error has occured

The following error(s) occured:

You may not fetch images from that site. To enable this site in timthumb, you can either add it to $ALLOWED_SITES and set ALLOW_EXTERNAL=true. Or you can set ALLOW_ALL_EXTERNAL_SITES=true, depending on your security needs.

Query String : q=95&w=70&h=70&a=c&zc=1&src=https://quast.blu.systems/wp-content/uploads/2014/04/1.40016_Querschnittplan.jpg
TimThumb version : 2.8.13