I have parent child squid installation. LAN->squid1->squid2->Internet. ^ ^ WAN squid2 works as a transparent proxy for WAN connections. I was using 3.2.13 for squid2 (child) and 3.1.23 (parent). Every thing works correctly. But, if i upgrade the parent to 3.2.13 or 3.3.8, i always get this error: 2013/08/06 09:54:29 kid1| WARNING: Forwarding loop detected for: GET /favicon.ico HTTP/1.1 Host: juventus.com User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:18.0) Gecko/20100101 Firefox/18.0 Accept: text/html,application/xhtml+ xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate DNT: 1 Cookie: __utma=1.525570529.1375757581.1375757581.1375757581.1; __utmb=1.1.10.1375757581; __utmc=1; __utmz=1.1375757581.1.1.utmcsr=(direct)|utm ccn=(direct)|utmcmd=(none); __qca=P0-214282750-1375757580942 Via: 1.1 otacon (squid), 1.1 solidus (squid) X-Forwarded-For: 127.0.0.1 Cache-Control: max-age=259200 Connection: keep-alive otacon is the hostname of child squid. solidus is the hostname of parent squid. The error only occur from LAN connection. Things work greatly for any WAN connection (with squid 3.1.23, 3.2.13, or 3.3.8). Parent config: http://pastebin.com/tsBCPJ5r Child config: http://pastebin.com/dz0u7g7b Thanks for the help. :)