kernel build failure

[andy at neu.net]

I am trying to build a new kernel on 4.9.release. I cvsup'ed the latest
ports and soureces right before I tried the kernel build.  I followed the
handbook, and when I typed /usr/sbin/config FIREWALL (name of kernel config),  I received the
following message:
[root at dell conf]# /usr/sbin/config FIREWALL
../../conf/files: coda/coda_fbsd.c must be optional, mandatory or standard
Your version of config(8) is out of sync with your kernel source.

What does this mean?  Do I need to upgrade config(8), how do you do that?
I checked the man page, but it didn't provide any insight.

TIA,

Andy