415 unsupported media type on some urls

[cocorossello]

Hi,

I'm having some 415 errors that i can't understand. It's not related to #3

This url fails:
http://imageproxy.niiknow.org/rx/100,r_90,e_50/http://www.tboholidays.com//imageresource.aspx?img=9eMP+0FIICgCIk6ZClzZH9Cs+1gwAq6BFWcc22yNLMF/UJIXMdxPdU6RmZuwTZuiS6rBEJmAZ68FHSG4vL99FBSK/CEPRKrDh1879afZSyUWbG4Ecg95EQ==

However the image does not seem to have a SSL issue

Do you have any clue?