cowboy crash when the browser send if-None-Match: "i0KCY3fxWkmxwUaTq08lH...

browser firefox 26.0 for ubuntu or chrome Version 31.0.1650.63 Ubuntu 13.10 (31.0.1650.63-0ubuntu0.13.10.1~20131204.1)

error log i had: (i put some trace in cowboy)

sorry wrong log