[warn] (2)No such file or directory: Failed to enable the 'httpready' Accept Filter

After upgrading Apache 2.2, you sometimes encounter the error "[warn] (2)No such file or directory: Failed to enable the 'httpready' Accept Filter" on FreeBSD.

You need load "accf_http.ko" by kldload.
(kldload can loads dynamically kernel module without rebuilding kernel.)

# sudo kldload accf_http.ko

And enable it in loader.conf

# vi /boot/loader.conf

accf_http_load="YES"